How do I change label names in Outlook calendar for other users?

I'm a delegate for one of my Directors and would like to know where in the country he is by renaming the colour-coded labels. it works in my own, but not in his. His still gives the default label names e.g. Important, Must Attend, etc. Any ideas?How do I change label names in Outlook calendar for other users?
Right click the coded labels and rename.

feel parents advice with

pets