Is it possible to save custom "profiles" when using DO on different PC's with different screensizes? I mean something like you can do in Photoshop, saving different layouts and open them with one click.
When reconfiguring DO I always have to copy changes manual on both PC's because my laptop has got smaller screensize and therefore needs a "smaller" toolbar and also other lister-layouts (less width) to fit.
You can save layouts using Settings -> Lister Layouts. They don't include toolbars, though.
You could make a button or hotkey which closes certain toolbars and opens other ones if your aim is to have an easy way to switch between different toolbars.
That's what I thinked about. Problem is you can't save different layouts when using special folders (like music, images,...).
Would be great if you could save complete layouts (mainly lister & active toolbars). Also UBS-export would take advantage of this when using DO in different environments.
Why not?
??? Does lister layout save ALL folder-layouts?
I saved 4 layouts within settings (FTP, Music, Videos and standard folders)
Not sure what you're asking.
If you save a layout it saves the state (window position, open folders, folder tabs, folder formats, etc.) of one or all (depending on what you choose) open windows.
I'll never understand difference between foldersettings and layouts 
In folderformat-settings I have defined columns, width, viewmode... for 4 different folder-contents (filetypes).
In Lister-Layout I saved view-mode.
In lower resolution I need smaller width of columns for each folderformat to avoid vertical scrollling, also toolbars must be reduced (but this can be simple solved switching between different toolbars).
Layouts save the format. (But if you then do something which causes the format to change, the new format won't have anything to do with the layout. You could save the layout with the format-lock turned on to make sure it doesn't change, though.)
You can also set up Opus the way you want for one computer, and then backup that configuration for that computer giving it a specific name (eg desktop). Next set up another configuration for another computer and back that one up with a different name (eg laptop). Then to switch from one complete configuration to the other, you just restore whichever backup you want.
That's the same I do now. I have two configs, but as mentioned before changes on one requieres to change the same to the other. That's why I like to have one with just different layouts. Won't work 
Even with the format lock on?
Did not try, but theoretically this won't help, because I have to reconfigure the format when copying config to another.
Why?
One machine uses one layout (with its locked format) and the other machine uses another layout (with its locked format).
The only time you have to reconfigure either layout/format is when you actually want to change them.
Alternatively, you could keep all all the configuration files in synch except for the /dopusdata/Formats, Layouts and ListerStyles directories. (And maybe some of the files below Buttons for the toolbars you want to be unique on each machine.)