Every team you belong to shows up in your teams list, either in your favourites or inside the More menu at the bottom of your list. Reorder your teams to focus on the ones you're most active in. See this support article from Microsoft Support for instructions: https://support.office.com/en-us/article/reorder-the-teams-list-afe19b9e-b6e8-4a6b-8627-dddb4f774b65
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