It uses your nip65 relay list if it can find it.
You currently can't change your relay list in the UI, you would have to do it with another client.

If it can't find the list then it uses
- nos.lol
- einundzwanzig.space
- nostr.oxtr.dev
- relay.mutinywallet.com
- nostr.fmt.wiz.biz
- relay.nostr.wirednet.jp