You tell them that at startups, titles are total fiction not used to describe job responsibilities but to participate in a branding effect for the company.

And then you describe your actual duties and experience.

I don't think titles matter at all because they're always different everywhere you go. The only exception is if you're a committed ladder climber and you're going from one place with a rigid hierarchy to another similar place. In this case jockeying for title position can be important.

You tell them it was the title for a customer support role at the startup you worked at.

Most of those people will likely end up at other startups anyway.