How to change the main admin on a mac m4

When you find yourself fiddling with Admin accounts...

Before you change ANYTHING, I recommend you create a NEW Admin account that you will use just for administration, or in case of emergency. Write the password on paper, and set it aside in a safe place. You may never need this account.

if your changes to 'Who is an Admin' go badly wrong, you could end up with NO Admin accounts, and that can lock you out of everything. Then your new Admin account can be used to rescue you.

I agree with @MartinR it is best to keep your original admin user account. Having a second admin user account can be useful if for some reason your wife is unable to log into her own user account. Plus last year some people mentioned having their admin user account mysteriously changing to a Standard user account. If there is a second admin user account, then it makes it much easier to try & fix the problem, otherwise you will be erasing the system & restoring from a backup in order to fix the problem.

Plus as @MartinR mentioned, very little is known about the new concept of "Ownership" & the ownership certificate. I have seen people reporting macOS "ownership" issues...usually associated with cloned external boot drives, but I can also see it occurring in other ways (I've seen a lot of things with the security enclave chip settings....more on the Intel Macs than M-series Macs though).

You can make your wife's account an admin account and she can administer the Mac. If you have data files in your own account that you want to "transfer" to her you could just move or copy them to her Shared folder ... or IMHO even easier just put them all in a single folder and change the permissions on that folder for Everyone = Read & Write and apply to all files contained in the folder.

In general terms there is no real priority among multiple admin users ... all admin users have the same privileges except that they each have their own user account. But there IS one difference that applies to the first created admin account on the Mac, for which reason I strongly suggest that you NOT remove your current (what you called "main") admin account or change its status to Standard User:

1. It was the first established account on the new M4 Mac. That account is the only account that has something called the Owner Identity Certificate (OIC) associated with it. Not much is known about the full purpose of the OIC so it would be prudent not to disturb the admin account it is associated with.
2. One area where the OIC comes into play is if you ever attempt to install a new boot volume or install macOS on an external drive ... you will only be able to do it from the admin account that is the Owner.

Also, it is good practice to have at least 2 admin accounts on your Mac so you are not left high-and-dry if your only admin account were to go bad for some unforseen reason.

For a bit more information about Ownership, see this article: Ownership means two different things in Macs: how to tell them apart

Open the Users & Groups section of System Settings, click on the I button for each account, and change its status. This won't change any files, but those should be backed up.

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