If only you would have used the top function "Columns ..." in the context menu of a column header ...
That function opens a nice dialogue in which you can:
- define all the columns that you want,
- rearrange the order
and it stays open until you click OK or Cancel.
For the auto-size feature: have a look at this thread:
Other features that might be of interest for you is the search function in this forum so that you don't have to start a new thread for old topics all the time and the help for MP3tag which can be accessed either by pressing F1 or via the address help.mp3tag.de which would have revealed most about the columns and even explained
What is the Tag field?