Dewalt DC925 Cordless Drill "keyless chuck reverse bit" Questions

...use keyless chucks these days. Shift the drill into reverse and hold the main body of the chuck. Pull the trigger and the bit should come out. Put it into forward and run it to tighten onto a new

DeWalt DC925XE Keyless chuck keeps undoing when reversing screws releasing driver bits. You must never oil the chuck so if this has been done then it can be the cause of your problem