Edit as needed.

I re-installed Devuan 6.1.1 (Excalibur). During installation, I supplied only a User Name and User Password. (I bypassed the prompt to enter a Root Password.)

Good to know that you have deciuded to follow the sudo path. Important for further support.

My guess would be that these partitions have been mounted already during system boot, and you are just opening them with Dolphin. Without looking more into the details, we can't say for sure, but the inxi output is enough for a qualified guess.
From there I can read that you have / on sda11, /boot/efi on sda1, swap on sda10 and /home on sda9. These partitions can be accessed by Dolphin w/o any additional mount because they are listed in the fstab which defines which partitions will be mounted during system boot (swap will remain hidden). To confirm please execute:

cat /etc/fstab

Looks very normal to me. sda7 seems not to be listed in the fstab since its not listed in the inxi report, so when you want to mount it you must enter your admin pw for elevated privilegues for this activity. This requirement is part of the Linux safety philosophy.

You can't bypass this procedure, except for when you follow pcalvert's advice: add sda7 to the fstab. Then its mounted during bootup and everything required is handled in the background.

All major DEs like Cinnamon, Gnome, KDE, LXQT, Mate ... have so called automounters on board that take care for removable drives. These automounters handle the elevated privilegues in the background and supply the drives mostly in /media/$USERNAME/drive with access for the user. This is also valid for e.g. USB sticks or drives that are extx formatted or usb disk drives with any file system or encryption.

If you frequently mount that sda7 partition, try adding it to your fstab file and configure it to be mounted automatically.

Opening the Dolphin file manager, I found that I needed only to click my partitions to mount them-- except for just one partition, Media1 (sda7). After clicking on it, I got the following message:

Authentication is required to mount WDC WD1003FZEX-00MK2A0 (dev/sda7).

I had to enter my user account password to mount Media1.

I opened the Gnome Disk Utility, deleted the entire sda7 partition (Media1) and reformatted it as EXT4. After restarting, I opened Dolphin and tried to remount Media1 again by clicking on it. I got the same message: Authentication is Required. I had to enter my account password to mount it.

This is what I found in the KSystem Journal (the Authentication Log)::

2026-05-15T18:21:14.461306-04:00
homepc polkitd[1836]: Operator of unix-session:2 FAILED to authenticate to gain authorization for action org.freedesktop.udisks2.filesystem-mount-system for system-bus-name::1.57 [/usr/bin/dolphin] (owned by unix-user:martin)

2026-05-15T18:21:20.581825-04:00
homepc polkitd[1836]: Operator of unix-session:2 successfully authenticated as unix-user:martin to gain TEMPORARY authorization for action org.freedesktop.udisks2.filesystem-mount-system for system-bus-name::1.57 [/usr/bin/dolphin] (owned by unix-user:martin)

2026-05-15T21:02:45.699332-04:00
homepc polkitd[1662]: Error opening rules directory: Error opening directory “/run/polkit-1/rules.d”: No such file or directory (g-file-error-quark, 4)

The following is output from the inxi-Fzr Command:
System:
  Kernel: 6.12.88+deb13-amd64 arch: x86_64 bits: 64
  Desktop: KDE Plasma v: 6.3.6 Distro: Devuan GNU/Linux 6 (excalibur)

Machine:
  Type: Desktop Mobo: ASUSTeK model: MAXIMUS VIII GENE v: Rev 1.xx
    serial: <superuser required> UEFI: American Megatrends v: 3801
    date: 03/14/2018

CPU:
  Info: quad core model: Intel Core i5-6500 bits: 64 type: MCP cache:
    L2: 1024 KiB

  Speed (MHz): avg: 800 min/max: 800/3600 cores: 1: 800 2: 800 3: 800 4: 800

Graphics:
  Device-1: Intel HD Graphics 530 driver: i915 v: kernel
  Display: wayland server: X.org v: 1.21.1.16 with: Xwayland v: 24.1.6
    compositor: kwin_wayland driver: X: loaded: modesetting unloaded: fbdev,vesa
    dri: iris gpu: i915 resolution: 1440x900~60Hz

  API: EGL v: 1.5 drivers: iris,swrast
    platforms: gbm,wayland,x11,surfaceless,device

  API: OpenGL v: 4.6 compat-v: 4.5 vendor: intel mesa v: 25.0.7-2
    renderer: Mesa Intel HD Graphics 530 (SKL GT2)

  API: Vulkan v: 1.4.309 drivers: intel,llvmpipe surfaces: xcb,xlib,wayland
  Info: Tools: api: clinfo, eglinfo, glxinfo, vulkaninfo
    de: kscreen-console,kscreen-doctor wl: wayland-info x11: xdriinfo,
    xdpyinfo, xprop, xrandr

Audio:
  Device-1: Intel 100 Series/C230 Series Family HD Audio driver: snd_hda_intel
  Device-2: ASUSTek Xonar SoundCard driver: hid-generic,snd-usb-audio,usbhid
    type: USB

  API: ALSA v: k6.12.88+deb13-amd64 status: kernel-api
  Server-1: PipeWire v: 1.4.2 status: active

Network:
  Device-1: Intel Ethernet I219-V driver: e1000e
  IF: eth0 state: up speed: 100 Mbps duplex: full mac: <filter>

Drives:
  Local Storage: total: 931.51 GiB used: 503.88 GiB (54.1%)
  ID-1: /dev/sda vendor: Western Digital model: WD1003FZEX-00MK2A0
    size: 931.51 GiB

Partition:
  ID-1: / size: 115.2 GiB used: 6.67 GiB (5.8%) fs: ext4 dev: /dev/sda11
  ID-2: /boot/efi size: 951.1 MiB used: 10.5 MiB (1.1%) fs: vfat
    dev: /dev/sda1
  ID-3: /home size: 45.84 GiB used: 259.7 MiB (0.6%) fs: ext4 dev: /dev/sda9

Swap:
  ID-1: swap-1 type: partition size: 7.81 GiB used: 0 KiB (0.0%)
    dev: /dev/sda10

Sensors:
  System Temperatures: cpu: 25.0 C mobo: N/A
  Fan Speeds (rpm): N/A

Repos:
  Active apt repos in: /etc/apt/sources.list
    1: deb http://deb.devuan.org/merged excalibur main non-free-firmware
    2: deb-src http://deb.devuan.org/merged excalibur main non-free-firmware
    3: deb http://deb.devuan.org/merged excalibur-security main non-free-firmware
    4: deb-src http://deb.devuan.org/merged excalibur-security main non-free-firmware
    5: deb http://deb.devuan.org/merged excalibur-updates main non-free-firmware
    6: deb-src http://deb.devuan.org/merged excalibur-updates main non-free-firmware

Info:
  Memory: total: 16 GiB available: 15.49 GiB used: 2.18 GiB (14.1%)
  Processes: 218 Uptime: 9m Shell: Bash inxi: 3.3.38
martin@homepc:~/Documents$

Devuan GNU/Linux 6
KDE Plasma Version 6.3.6
Kernel Version 6.12.86+deb13-amd64 (64-bit)

... has additional EXT4 partitions that are non-Linux and had nothing to do with the OS install.

ext4 is Linux in any case. For the second part: as long as this/these partitions are not mounted, nobody sees them. No user, no root, no installer. No matter who the owner is.

First of all, you have not mentioned anything about what you have installed. Which release? Which desktop? You mention something about KDE later on. Would you mind to share the output from

inxi -Fzr

You may need to install inxi first.

Assuming you have not setup something like autologin, you should be asked for Username and password and not asked for any root/sudo password during booting and land into any root account.

Another fact: Root SUDO are not the same, they a two separate approaches to gain admin rights. We are here on a Debian based distro, not Ubuntu or like. The installer asks you if you want to assign a root password. If you say no, sudo gets installed and configured for your username (the Ubuntu setup). For admin actions you are asked for the user pw. If you say yes, the root account is fully generated and no sudo is setup at all. For admin actions you need to enter the root password.

Basically I can't follow your complaints and make any sense out of your problems. Why do you automount your media1 partition? What happens if you simply abort the mount request?
BTW: mounting is a admin action and requires root privilegues. Always.

Simple answer: NO

I hope my comments do help you to clear up some mist.

The same hard drive also has additional EXT4 partitions that are non-Linux and had nothing to do with the OS install. I have used the chown command to make sure that I am the owner of everything on those partitions. I use them to hold documents, articles, audio, and video. On one of these partitions, which is called Media1, I also had a copy of the Devuan Installation ISO. I used that ISO to create a bootable USB drive for the installation of Devuan, and I left the ISO on Media1.

Here Is My Problem
I believe that the ISO on Media1 may have somehow caused a problem during the OS installation. At least, that is the only explanation that I can think of for what has happened. This is what is happening:

Each time that I boot up (or restart), Devuan demands that I enter the Root SUDO password to authorize the mounting of the Media1 partition (which is sd7). When I enter the password, Media1 gets mounted, and I am logged onto a desktop that the ROOT created. It is not my personal desktop.  If I log out of this desktop and log back on, under my name and account, then I see my normal personalized desktop. The next time that I reboot or restart, I must go through this whole process again. I must give the SUDO password to mount Media1 (sd7), and I am logged back onto that alternate desktop.

I have re-used the chown command to make sure that I own the Media1 partition. I have also checked the file system using the KDE Partition Manager. Additionally, under System Settings > Device Auto Mount, I have verified that the Media1 partition is supposed to be auto-mounted at startup. I also looked in the KSystem Logs, but I found nothing related to Sd7.

Is it possible that Devuan somehow got the bootable UBS Install drive confused with the Install ISO on Media1? What can I do to fix this?