how to modify registry?

What error are you getting when you click on the link that appears when you hover over the "Click here to make a registry entry"? Keep in mind the actual link shows up on row 3 to the left side and that's what you need to click on. It opens up a Google Form that contains menus and drop down selection lists to help with making an entry. No entries are made directly to the sheet, the form is where all entries are made.

Thanks,
Mike

Assigned is most commonly used when you have a string of cars that you want to record as being in a specific track. For example LAC cars being assigned to S2.
Arrived is when you are making an entry for when a train arrives at the yard.
Released is the entry made after the train is completely assembled, has power added and is ready to depart.
Departed is the entry made when the train actually departs the yard and headed for it's destination.

Mike