Anchor Alert App Pro alarm tolerances are set once at the time the alert session is started. These cannot be adjusted for the current active alert session. If you change and save an adjusted alert tolerance it will be effective from when you start the next alert session.
You can adjust the anchor chain rode during an active alert session and the anchor bearing when using advanced mode. To do this, tap on the Edit button above the Anchor on the Anchor Map, then wait 10-15 seconds and adjust the chain rode, repoint your phone in the direction of the anchor, and then set the new parameters.
We are working on allowing more adjustable parameters during an active alert session such as the drag, swing and depth tolerance, however for now, you'll need to cancel the alert session, update the settings and start again.