Newbie - new user account reverts to old OS - why?

[Airscrew]

Used machine, new to me a couple days ago. Had only admin account, cleansed etc with no data. Upgrade successfully from 10.13 to 10.15. Then created my user account, with admin privileges.
So at login screen now, 2 users offered, admin or my new account.

admin is running 10.15.
New user is running 10.13.

before i start using the machine on the user account....

is this correct for mac os, or did i do something wrong?
What did i do wrong, and should i go back and do it differntly?
Or ignore it and upgrade the user account OS, and just start using it?

thanks to explain what is going on please.
J.

 

[Fishrrman]

If it was me, I'd boot to INTERNET recovery (NOT to "the recovery partition), then wipe the drive and start over.

If you're interested...

Internet recovery:
Command-OPTION-R
at boot.

If this Mac is connecting via wifi, you'll need your wifi password.
The internet utilities take a while to load -- be patient.

When the internet utilities are loaded:
Open disk utility.
IMPORTANT STEP: go to the view menu and choose "show all devices".
(if you don't see a view menu, don't worry about this and go to the next step)

Now, look on the left.
The topmost line is the PHYSICAL DRIVE inside.
Click on it, then click "erase".
Try "APFS with GUID partition format".
(If this fails, repeat the process to get back, and this time choose "Mac OS extended with journaling enabled, GUID partition format")

Once the drive is erased, open the OS installer and try again.
The Mac may reboot one or more times, and the screen may go dark for a few minutes with no other activity indicated. Be patient.

When done, you should see the initial login screen "choose your language".

If you try this, please post your results.

 

[chown33]

Please explain how you know the new user account is running 10.13.

If there's a window, such as "About this Mac", or something else, please post a screenshot of it.

If you used a Terminal command like sysctl kern.version, please paste the Terminal output here.

Also provide the equivalent screenshot, Terminal output, or whatever else you used to determine it's running 10.15.

 

[Airscrew]

Please explain how you know the new user account is running 10.13.

If there's a window, such as "About this Mac", or something else, please post a screenshot of it.

If you used a Terminal command like sysctl kern.version, please paste the Terminal output here.

Also provide the equivalent screenshot, Terminal output, or whatever else you used to determine it's running 10.15.

Hi Chown, thanks for getting back to me.
Nothing clever, as Im a new Mac user.
For both accounts (existing admin, and newly created user) I just used the Apple logo top left, 'about this mac'.

10.15 for admin and oddly 10.13 for user.