How do I set my spawn on a claimed island?

I placed down a Barrack but I can’t find anywhere to set my spawn in there, do you set spawn with a different building or did they just hide the prompt really well?

The barracks will have you (and clan members) spawn there on default

Instructions unclear, I somehow respawned on my Brig in the Bronze sea after I set the barrack down (without getting sent to the nimbus sea border)

Spawns are wonky like that idk how it even happens

I think it’s whatever is nearest.