Hi
I don't know how to do this! Sorry!
Can you have a 2nd user-login or profile that can have the screens set-up
differently? Is the problem down to having your desktop extended rather
than as an independent screen?
I use use Ubuntu with Gnome/Unity rather than Kde (ie as in Kubuntu). Kde
tends to have LOADS more options available easily but sometimes is
surprisingly sparse. On Ubuntu the "Control Panel" / "System Settings" has
2 or 3 icons for changing different features of the screens. The one that
lets you set resolution&aspect-ratio has a slider/tick-box to switch
between extending the desktop across the monitors or keeping them somewhat
separate.
However I think that is then set for the whole OS rather than per-user. So
one option might be to set-up a dual-boot / multi-boot by adding a fairly
small partition (maybe 25Gb? or less? Maybe 8Gb might be enough for
openSuSE?) to install an entirely separate openSUSE on. That could be on a
Usb-stick.
Another option might be to find how to run an entirely separate X-server
with it's own xorg.conf but I've never tried that and idk what happens
about mouse-keyboard or android-remote(?) sharing. The apps store for
Android has an Impress app that is specifically for making a handheld
(phone or tablet) or perhaps even a wearable into a remote control unit
that should magically find whichever screen is running the Impress
presentation.
I'm kinda hoping someone has an answer inside LibreOffice or at least has
more knowledge about Kde!
Apols and regards from a Tom