As a teacher, you can specify which subjects you teach via My settings. You then get shortcuts in the Library to tools in your subjects.
How to:

Click on the profile icon at the top right. Click on My settings.

Search for your subjects, click on the magnifying glass. Click on the subject.

Repeat until you have added all the subjects for which you want shortcuts (buttons for a maximum of 3 subjects can be displayed).

In the library, you will then see shortcuts for the subjects you have entered.