Making slave into master on another inspire.

I'm having trouble making a slave from one Inspire, the master on another. This would be a permanent switch. When I go into RC on the DJI app I don't see the master/slave option where I get to choose. When I click "link" -'d hit ok nothing happens, no 60 second timer.

I've tried the C1+C2+video+camera dial, but not sure if I'm doing it right. Any suggestions? Thanks for reading!