The Americanism of calling people by their first names does not work all the time. It is an artificial manifestation of egalitarianism.

I have observed that many former students have tried calling me by my first name, which is fine with me except that they rather than I seem permanently uncomfortable with it.

I think, as a rule of thumb, before calling a superior by their first name, consider the following non-egalitarian realities:

--did the person attain a higher educational level than yours?
--does the person have more accomplishments than yours?
--does the person have more credible experience than yours?
--does the person have a better curriculum vitae than yours?
--was the person awarded by society more than once?
--is the person making a bigger difference than you are?

Superiority has nothing to do with having a higher-paying job or a hefty bank account. That, as a matter of fact, is the wrong notion people have about "egalitarianism".

It is highly probable that this is a non-egalitarian world, but maybe only you can answer that.