Admin screen resolution problem

I have two WordPress installations and the WordPress admin screen/back end for each has a different resolution size. One has a resolution of 1024 and the other 800. This is only in the WordPress back end/admin area, mind you, not on the front end/site itself.

I have tried changing themes, disabling plugins, etc, to no avail. It seems that this setting is hard coded into WordPress?

I want them both to be the higher resolution, as the 800 looks a bit blurry. How can I adjust this? Thank you.