Making a tier non-editable is to avoid putting that tier in edit mode while navigating through the table . For instance if some of the tiers of the same type are transcribed and few are not, to avoid the transcribed ones to get in to edit mode the tiers can be locked(made non-editable). To freeze/unfreeze the tiers, right click on the tier name (if shown) or right click on any of the locked or unlocked annotation of the tier will popup either this menu - see : Figure 3.5 or this menu - see :Figure 3.16. In the popup menu select make this tier non editable to freeze a tier or select make this tier editable to unfreeze the tier.