Haha,
imagine something, im german. And learned so good i could english a little bit.
So you could learn German too! Dont be so lazy! 
Just Kiddin.
On you, this would be the menu “view”, than maybe “screen scaling” (or something similiar) and then “resolution automatic adjustment with window”
Or, you could simply look what menus looks similiar from the position 
Here is the problem. It’s screen is fiull in the vm window but nothing works when you click on them unless you go to full screen mode!
Edit: I repeat nothing works inside the vm window!
Edit: This is how i use it on v-box and vmware …no issues!
Step by step.
So the automatic screen adjustment works now? And your problem is only, that if you use it this way, input didnt work?
In fullscreen mode like this then it works. I can click on anything and they work.
Update:
First attempt failed because I failed to understand mounting properly. I am using this video by EF-Linux along with the arch installation guide as my references. The main difference is that Ermanno is using GPT with UEFI while I want to use GPT with BIOS.
I was confused whether I can run the command given in Arch Wiki - Grub
grub-install --target=i386-pc /dev/vda
after changing root to mnt
arch-chroot /mnt
without mounting the grub partition. I’m planning to see the entire video, taking notes and then attempting it again.
Ok. could you just for testing change the “Videocard” to QXL?
And/or test to Click in the middle of the “screen” and press Ctrl_l+alt_l
Qxl won’t work because it doesn’t set it to fit. It’s too big and has scrolling.
that wasnt the question.
The Question was, if you have input if you set it to QXL 
Sorry yes… i think so…
Edit: Yes it does but screen is too large.
Edit2: Looks like I’ll have to settle with qxl and 1600x900 close as i can get. This sucks comapred to v-box and vmware.
Ok. So we know whats your specific problem is.
Do you use wayland? Latest Kernel?
Edit, could u test a Ubuntu Live CD for example with the virtio gpu?
No wayland for me. Latest kernel. I don’t believe in using lts kernels. Otherwise i’d use Debian. This is rolling.
Mint is ubuntu!
Edit: Okay I’ll try it just for fun.
What? I was talking about the VM. If you could boot a Ubuntu CD into the VM.
But since you mentioned, you dont use endeavouros as your OS?
I’ll try Ubuntu. I use what ever you want. 
Edit: I’m installing it!
you confuse me 
just to be clear. i help you so good as i can. but if your not using endeavouros and intead Mint, it makes troubleshooting a lot more harder/complicated, because the Software included in Mints repositories is already rotten away at release of the Distribrution
With virtio as gpu? and you could use keyboard an mouse?
Of course i use EndeavourOS! I just trying something else.
Just as suggestion, because you have “Forum Moderator” in the Name.
Wouldnt it be better, if you open a Thread about your problem, and move our conversation in it? So this thread didnt go OT.
Sure.
Edit: I think i’m going to try virt-manager again on my Intel system with Nvidia.
First Arch install successful. 
Going to setup i3 later.
Can I say “I use Arch btw” now? 
Normally use gnome boxes just because of the ease of use