"It was better when you could log in under a separate user name under
Youtube and still be able to check into and out of Gmail without it
You still can but it works a bit different. For example - I log in here tho this forum, which in turn logs me into Gmail, and if I go to YouTube it logs me into my YouTube account as well. ( and it can be done in either order ).
But on YouTube, if I click my username at the top, I can log into a different YouTube account(s), and logging into successive YouTube accounts does not log me out of here or from Gmail - it only switches the active YouTube account.
Then the YouTube accounts can be fast switched back and forth without having to manually log in again. And also is an option to log out of all accounts which will log me out of all Youtube accounts, pls here, plus Gmail.
It was difficult to get used to at first, but I like it now.