Sounds like you have quite a small screen/resolution.
The sections of the dialogue box will close by default when you open another and they both can't fit on the screen.
There are options in your Work Environment you can play with but you may find you then have to go hunting for what gets pushed off screen.
Although for me at the moment in 25 they don't always seem to work as expected when I turn them off.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10