After Server Upgrade, Needing Help Updating SSH Keys Settings

Hello, our website's server was recently updated to something newer (from CentOS 7). And normally, I connect to this server over SSH (using Windows PowerShell). And after going through a process of creating new public/private keys and installing them on my computer plus creating a new passphrase, etc., now everything is working just fine on that side.

So next I attempted connecting to the server using WinSCP, and at first I saw a prompt with the option to 'Update' my settings - which I did. I was expecting to see a password prompt after that, where I'd put in the new password and be in ...

But unfortunately, that's not what happened. Instead, I saw this message (and see it every time I try connecting now):

No supported authentication methods available (server sent: publickey)

Authentication log (see session log for details):
Using username "myusername".

Authentication failed.

I think the issue is that the previous private key lived on my computer in a different location from where the new key is ... But after spending over an hour reading online documentation and trying a few things, nothing is working for me.

Note: I am doing this with a computer running 'Windows 11 Home' and am also on the latest version of WinSCP.

It's probably an easy fix, but I'm finding it hard to figure out and therefore any assistance will be appreciated!

Thanks,
Jim