New vs Old Folder

I am attempting to make some changes to a page.php file for a wordpress site. Using FireFTP, I’ve accessed the FTP and found that there are two folders: a “domain” folder and a “domain old” folder. First: any idea how/why I’ve got both?

And then the larger problem: I would assume that any work I do should be in the domain folder, rather than the domain old folder. But the child theme I’m using in WP only appears in the old folder, and while I can move a page.php over to that child theme folder, it does not appear in the wordpress editor. I’d really like to be able to edit there. (I have not tried yet to edit offline, so I don’t know whether edits made there would translate to changes on the page. That’s my next move.)

So my questions (and please excuse how ridiculously elementary they are; I’m learning as I go) are: (1) is it a problem that the theme only appears in the old folder? (and if so, how do I get it to move?) (2) and if not, is there something I should be doing to make the file appear in the editor?

(If (2) is really a question for wordpress support instead, no problem. Any insight you could offer into the “old” and “new” folders would be appreciated.)

The old folder comes about when you upgrade your wordpress version if you’ve used the 1-click install.
Using FTP you can move or copy the theme from the old to the new…

The old folder can be deleted once you’re happy the upgrade is working properly.

Great! Thanks!