The regular depth chart gives you the ability to generally specify the position that each player will play in. You may want to, in certain situations, change out players, i.e. if you have a pass rushing DL who is poor against the run, you might sub him in on nickel and dime packages.
If the player is yellow on the overrides, it means that the player was from your general depth chart. A red indicator means that this is a player that has been overridden - that he will stick there regardless of what you do in the general depth chart.
If you reset your depth chart to your coach's recommendation, all the depth chart overrides are removed.
Hope that helps!
