"Main Panel" is the official name for center panel. Click the button to the left of the Search box, choose Main Panel->Tracks. Right-click the Tracks bar and set your Displayed Fields (Filename, etc.). Now drop the header menu in the Tracks panel, and choose e.g. Artwork->Medium Picture. Etc.
There are about 3 other ways to approach this "but this way is mine."
You would lose a lot of nice options by totally blocking MB from the Internet that have nothing to do with modifying the files unless you tell it to. Internet radio, lyrics and artwork finding/display (NO "SAVING" UNLESS YOU CHECK THAT OPTION), CD AccurateRip checking, identifying songs via fpcalc.exe, etc.
Making your whole Music file folder "read only" works too in the no changes department, but so does hunting down and un-checking all the options that might do so. More time consuming, but a good way to learn about where all these options are and others that you may not know are there but WANT to use once you find out.
Unfortunately the complexity of MusicBee is not served by its poor documentation. The user forum "pinned" areas, and using the hiccup
forum-only via Google searcher are excellent ways to learn. Don't forget that using the Portable version of MusicBee will easily allow you to back up its SINGLE FOLDER with ease every time you want to try a new configuration and return to the previous with a single copy-paste operation. Worry-free experimenting, perhaps the BEST way to learn.