Superadmin Single Sign On for all subsites

Good afternoon,

I hope you are all doing fine.
I have a question regarding SSO when logged in as a super-admin: I need the wp-admin-bar which requires that I'm logged in, otherwise I don't see it. So, I log in on my Multisite with the super-admin credentials, which works fine. But as soon as I try to have a look at a (sub-)site, I'm logged out and don't see wp-admin-bar anymore. Another weird issue is that I can not log in on (sub-)sites using my super-admin credentials (password is correct).

I've looked through the settings, searched the forums but that didn't help. Can someone help me out please?

Thank you very much,

Have a nice day.