Reverse Thrust Not Activating

How do i activate reverse thrust. Pulling down the throttle does not work. Iam using an iphone 6

When are your trying to activate reverse thrust? If the plane is below I think 50kts(correct me if I am wrong) reverse thrust will not activate when pulling the throttle all the way down.

Reverse thrust won’t work in flight and below 30-35 knots.

Not sure if it works on taxiways but you shouldn’t be going above 35 kts. on a taxiway anyway.