Tell your lessons which words you already know
Choose "I know this" on a glossary word and your lessons stop underlining it, in every course.
Lessons underline the words that have a glossary card. If a word is old news to you, open its card and choose "I know this". From then on it reads as plain text, in this course and in any other.
To clear a whole list at once, open Words in the course index. Every word has a circle beside it, and filling it is the same as "I know this".
A word also goes quiet once your work in the course shows you know it, or when you tell your Maestro so in the chat.
Nothing is lost. The words you know stay in the list under You know these, and in Your words on your home. Turn off "I know this" on one and it is underlined as before.