Cam App iOS iPhone 15 Pro How to Lock ISO?

Hello, thanks for having us at the forum. I’m having trouble with using the Blackmagic Camera app on iPhone 15 Pro, latest iOS. I can lock some settings but not the ISO if I’m touching for rack focus or refocusing on a new person or object, even if I set it to a fixed point like 800, it changes as I’m shooting. How can I freeze the iso but allow for touch focus?
Also every time I tape a new focus point like rack focus it resets the iso and won’t save my settings??

Thank you.