How do I save a repository settings to get back after disconnecting and connecting to another repository?

I am using Kopia UI on Mac.

Well… KopiaUI doesn’t support config sets, but you can connect to multiple repos at the same time. KopiaUI stores its configs under

~/Library/Application Support/kopia/repository[-<id>].config

if you want to save those, feel free to do so, but I don’t know, if messing with these config files manually is a good idea.

Found it:
The toolbar is your friend.

Mac only.

Well, not the answer to the question itself, but yes… that’s where you can connect to multiple repos. However, when you disconnect from them, e.g. when starting KopiaUI and one ore more repos are unavailable, you need to remember to leave those alone, until the repos are available again. It’s rather easy to accidentially disconnect from them or remove them otherwise.