How to use perforce after updating?

So after a lot of fiddling, I finally got perforce working and playing along with UE 4.23 a while back.

But I recently updated to 4.25 and thus need to implement perforce all over again.

I made a new depot for the new version, and a new workspace for my new project folder.
However, I cannot for the life of me figure out how to change the depot you submit files to.
When I try to do the initial add of the files from my workspace, it adds them to my old mainline depot.
I cannot find any way to connect my new workspace to my new depot rather than my old one.

If I try to connect it to the stream directly, only the old one show up as an option, not the new one.
Any suggestions?

How do I make my new depot the mainline version?