macOS is a multi-user operating system.
Your husband and you should have also different user accounts on that same mac.
If you are both sharing the same account, but have two different e-mail accounts both in the same Mail instance, the best one can do is click the little arrows and collapse the intermediate stuff. This will greatly reduce the length of the sidebar and bring your account far up.
In this screenshot there are "Favorites", "On my Mac", "Account 1"' and "Account 2" all collapsed, so
"Account 3" appears quite far up and there is no need to scroll the sidebar.