The article outlines the steps to add stock adjustment reasons
FOLLOW STEPS BELOW:
1. Click Administration -> Lookups -> Stock Adjust Reasons
2. Click the ( + ) icon and enter the Reason
3. Mark the Reason as Active
4. Check the boxes where this reason can be used
Note: For Out Adjustments make sure the "In" tick box is *unticked*
NB. For a quick tutorial watch below