Hey there!
First, can you provide more details on the issue(s)? Otherwise:
With what you described, here are my thoughts:
Did you move data from an older Mac to the new Mac?
Do you have Find My enabled for this Mac?
If you just set this up, and one or both answers are Yes, I might save yourself some time and do this:
—Make sure you have everything backed up.
—If you can, sign out of your Apple ID in System Preferences > Apple ID > Overview.
—Otherwise, “Remove” this Mac from Find My on one of your other devices, or at iCloud.com.
—Shut down your Mac.
—Startup your Mac, continuing to hold the power button, until you see “Loading startup options”.
—Next, when it asks for the password, look on the top left menu bar, by the Apple logo.
—From there, click on Recovery Assistant > Erase Mac.
—Once the Mac is erased, it will restart, and you might be prompted to “Activate” this Mac, go ahead and do that. (You May he asked for your Apple ID and password, so make sure you connect to your network before clicking on “Activate”.
—Next, click on “Exit to recovery”.
—Finally, select “Reinstall Mac OS”, and install the OS o by our Mac again.
After those steps, you should be able to migrate your data back into your Mac from your backup, or simply set it up as new, sign into your accounts, or anything needing to be done.
I know it sounds complicated, and I could be wrong, but I’ve seen this as well, especially with the admin password not being accepted, for any or all users. I believe it has to do with the new security, whether iCloud and/or the Mac OS security, especially not liking a migration from an older Mac or OS.
I could be wrong, and your issue might be different, as I don’t have all the details, if so, let me know! But from what I’ve seen myself, erasing/reinstalling specifically using Recovery Assistant should fix any problems.
