There is no problem, I am the problem. I do not know how to remove icon on the Panel(Widget).
I have solved the newly occurred problem by remove the Panel and add the Panel(Default Panel), then can add and delete(remove) the icons on the Panel(Widget).

1. Search an application,
2. Add to the Panel(Widget),
3. Right click the icon(On the Panel/Widget)
4. Enter Edit Mode,
5. Cursor floats on the same icon,
6. then appears "Remove", and click, OK.

I have tested it in the virtualbox, same as the host pc, and found out  it is true.

devuan_daedalus_5.0.0_amd64_desktop.iso
session: KDE_Plasma

Thank you.

Perhaps you need to write down the full name of your Devuan.iso, the session(Gnome/KDE_plasma/Mate/XFCE, etc),

and how you installed the firefox,

for example:devuan_daedalus_5.0.0_amd64_desktop.iso

so other people may test it again.

Thank you.

My sources.list is as below:
sudo nano /etc/apt/sources.list

deb http://deb.devuan.org/merged daedalus main
deb http://deb.devuan.org/merged daedalus-updates main
deb http://deb.devuan.org/merged daedalus-security main
#deb http://deb.devuan.org/merged daedalus-backports main
#deb http://deb.devuan.org/merged daedalus main non-free-firmware non-free contrib

I used "no-free" sources for the first,second...times, but later, I commented out "no-free‘ sources.
Today, I used "no-free“ sources again, but Kaffeine does not play some special mp4 files well, many mosaics.
Any way, I can use Kaffeine to play other mp4 files.

Thank you.

"not work well(same as VLC): kaffeine(VLC based mp4 player).

VLC: Hardware-accelerated decoding-> Disable"
------------------------------------------------------------
I did not find a way to change the Kaffeine mp4 player default settings.

How to use command line to change the Kaffeine settings?

If there is no way, I will not use Kaffeine for a while.

Thank you.

No,

please choose devuan_daedalus_5.0.0_amd64_desktop.iso.

I only say I installed devuan_4.0 years ago.

Rufus can work normally to create a bootable usb.
Now I use dd(linux) to create a bootable usb.

I do not know how to partition, so I choose  "All files in one partition".

Please try again.
Use another pc or smart phone to see the steps of installation guide, and install the iso again.
Please write down the details of the steps of installation.

I follow the below guide,
https://www.devuan.org/os/documentation … installing

diffrent from yours:
https://www.devuan.org/os/documentation … s/live-gui

You can check the bios, to see if there are any boot system.

Thank you. It works. Now VLC plays the same mp4 file normally.

VLC->Tools->Preferences->Input/Codecs->Input&Codecs Settings-> Codecs->Hardware-accelerated decoding-> Disable(choose: Automatic/VDPAU video decoder/Disable)->Save.

Many thanks to you all.

I uninstalled vlc, then installed debian deb file:vlc_3.0.18-2_amd64.deb
Open the same file, nothing changed, there are some mosaics, the pictures are not acceptable.

It is strange that the same vlc version works well in MXlinux-23.

vlc message:
https://paste.nolog.cz/?bcad128b3763b19 … mHtXJ9yoLf

mp4 file
Warning: size, 715.86MB
brush_up_life_japanese_movie.mp4 (715.86 MB)
Expiration: Saturday, September 9, 2023 2:16 AM

download link: may take a long time to download.
https://upload.disroot.org/r/ReA6f33n#E … nxjknMia0=

Thank you.