Choose file management software when opening Download folder

[Postbox8420]

Hello,

Usually I’m using dolphin, but I’ve installed Nemo too for having a second option if dolphin doesn’t work.
But after installing Nemo the file management software when opening the folder where the file downloaded (e.g. for Firefox, Signal, …) switched to dolphin. Where can I change it back to dolphin?

I’ve already checked all file assignments and for the file management software in default applications is dolphin set too.

System Information:
Operating System: Manjaro Linux
KDE Plasma Version: 6.2.5
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.1
Kernel Version: 6.12.11-1-MANJARO (64-bit)
Graphics Platform: X11

[eugen-b]

@Postbox8420

But after installing Nemo the file management software when opening the folder where the file downloaded (e.g. for Firefox, Signal, …) switched to dolphin. Where can I change it back to dolphin?

Maybe you mean “switched to Nemo”? Or “change it back to Nemo”?

Anyway, easiest thing is to uninstall Nemo.

[cscs]

@Postbox8420

But after installing Nemo the file management software when opening the folder where the file downloaded (e.g. for Firefox, Signal, …) switched to dolphin.

Regardless of the accidental mixup … I also think you might be mistaken - in these cases it is neither nemo nor dolphin nor any other proper file manager but some interface of xdg-desktop-portal.

Portals should be properly configured, with the chosen backend.

XDG Desktop Portal - ArchWiki

I read it again and now think we are actually talking about a file manager.
“Opening containing folder” or “Show in folder” options indeed open a real file manager.

PS.

@Postbox8420

Usually I’m using dolphin, but I’ve installed Nemo too for having a second option if dolphin doesn’t work.

The starting point of this is a bit funny - dolphin rarely if ever would not function. I might expect in cases where dolphin does not work its a case of a totally dead GUI.
But if we accept that premise I would also suggest just about any other file manager aside from nemo or gnome-files.
Another qt one would make the most sense on your environment, but even other gtk ones would be preferable over nemo/gnome-files.
If its serving as some sort ‘backup’ I might also think something minimal would make sense - like pcmanfm-qt.
Or even a terminal based one like nnn.

[Nachlese]

I concur with @eugen-b - uninstall Nemo and all the the things it pulled in along with it.
Nemo is a GTK application - typically not what you want or need in a QT/Plasma environment.

If you just need a second file manager - install mc (Midnight Commander).
It is a console/terminal application and it will always work, whether in a graphical environment or at a TTY. There are graphical variants of it, too.
And it will not interfere with Dolphin being registered as the default File Manager.

I do not use Plasma often and am not very familiar with it, but I’m sure that you can set Dolphin as the default somewhere, even with Nemo installed.