Missing Savebutton in the program for Imac

[ohrenkino]

See e.g. here:

How to you save changes in MP3 Tag

Hi, I bought the MP3Tag app yesterday via the App Store (version 1.6.1) I can't seem to save any changes that I am making to my music files and was wondering if you can tell me how to do this. The downward arrow "save" tab in the tab bar (just above the word "Filename") is greyed out and so it won't let me save any changes that I have made to the music files. Are you able to please help on this? Thanks Will