Its based on whatever lnurl is in your profile

I do this. Primal always sends from its built in wallet. Just make sure your bitcoin lightning address is the coinos one in your profile (this is shared across clients). You can see my profile in Primal below (if I use primal to zap myself the sats will leave my primal wallet and be deposited at my coinos address). You can actually put any wallet address here (they’re called LNURL addresses). Primal gave you one too when you signed up for Primal (username@primal.net) so you can always re-add that if you want to receive zaps to that address.