Hi louisaandgreta,

Many courses on the site have been getting updated recently. To see a full list of courses that have been getting updates please see this article: https://support.khanacademy.org/hc/en-us/articles/4405120369037-Content-Update-Course-Updates-are-on-their-way-in-late-July-2021. Scores for quizzes and unit tests will not disappear after a certain amount of time, but content updates may affect the mastery percentages. 

I hope this helps! Please let me know if you have any further questions.

There hasn’t seem to be any updates for arithmetics and yet it no longer shows that I did the quizzes and unit tests, they are no percentages next to them anymore, and I’m not talking through the app but directly on the site of course. As for my mastery percentage scores for each section and for the whole arithmetics course have not changed. 

The same happened in Pre-Algebra, where there has been updated content, and my mastery percentages have not changed but all my quizzes and unit tests percentages have been reset. 

Sorry for the delayed response!

This issue would be best handled by a member of the support team — could you please submit a support ticket so that the problem can be further investigated? When filling out the ticket, it will be helpful to include a detailed description and screenshots if possible.

Thanks!