I saw this question come up quite a lot, however none of the posts, threads etc. I found did not help me to solved my problem.
Let me explain my situation. As a host OS for my VB I am using Windows 10 64-bit and I am running Windows 7 64-bit as a guest. Win7 in VB runs fine, just for one think. I can't set resolution to 1920x1080 (however I managed set it to 1920x1200 and higher), max resolution of my monitor.
After very quick research I figured out that somethink called "guest additions" exists, so I installed it.
- Devices -> insert guest additions CD image...
Installation began and finished sucessfully (at least it looked like it did) and I rebooted the guest OS. But nothing changed. "Seamless mode" and "Auto-resize Guest Display" in View menu are still greyed out and if I fiddle with the window size as much as I want, the guest resolution doesn't adjust and stays static.
I tried install Guest Additions twice then reinstall it etc. I read thru handfull of threads and posts about this/similar topic but I didn't find any answer and I am basically clueless now. Maybe I am disregarding some basic think as usually?