Good afternoon, @Saniyah ...
It sounds like you're trying to submit a Feature Idea here in the Community rather than asking a question in the Question Forum area of this Community website. Thankfully, a similar existing Feature Idea has been submitted that you might be interested in taking a look at: Marking all announcements read. If you feel that this Feature Idea aligns with something you'd like to see implemented in Canvas, I would encourage you to "rate" the idea and also maybe post a comment to the bottom of it letting Instructure engineers know why this would be important to you in Canvas.
I hope this will help a bit. Let Community members know if you have any other questions about this...thanks! Take care, and be well.