How do you automatically set the program to update tags for all your tracks??
That depends on what you mean by
The biggest chunk that can be tagged in one go e.g. by web source scripts is an album.
Or if you want to change the genre "Pop" to "Pop Music", then you can filter for all those files and treat them in one go.
What Mp3tag will never do is "guess".
there are several ways using web sources to complete tags like album and year, please use forum search.
You may have a look here: