Hi @MarissaBarreto,
That behavior does sound unusual. I'm wondering if it's perhaps a combination of login timeout settings plus your school's login perhaps being web-based that are causing the issue. Unfortunately, community members are mostly other Canvas users like you, so while we can speculate a bit here, the best thing you can probably do is reach out to your local Canvas team (usually in the eLearning / IT / Digital Education areas) to report the issue and hope they can either adjust their settings or provide some kind of workaround for you.
I hope this info helps, even if it's not quite a full solution.
-Chris