???? could try this
You sign into Youtube with a Google account because it's a google product, not Microsoft. You may have used a Microsoft Account address to sign in to Google, but that is only because (like Microsoft) Google lets you use any email address you want to create a Google account. It is still a Google Account.
To change to another Google account, go into Youtube.com, at top right corner click on your account icon, then Manage Google Account, then in the Google Account click the same icon and this time Sign out.
Now click Use another account and sign in with the MS email address you want to use instead. It should still be available as it only goes away if you close it.