Microsoft ファイルのホスティングおよび同期サービス。
Thanks for clarifying. Please check this question. Are you and your family using different Windows user accounts when you each sign into the PC?
If you are using separate Windows profiles, Microsoft’s own support info says each user with their Microsoft account and a shared subscription should keep OneDrive and Office data separate.
This suggests something unusual if your account still appears in their profile. You might want to confirm if the OneDrive/Office login under their Windows profile was ever signed in using your credentials.