How do I reschedule water softener regenerating

I have a Water Pro Water conditioner. Its about 10 years old. It is scheduled to regenerate at the worst time, 1 AM at night. Its so loud that it wakes everybody up in the house. I have tried fiddling with all the buttons, and I havent been able to figure out how to reschedule the regeneration cycle. Is this something that has to be done by a professional?

The visible buttons are (in order): Change, Select, Display, and Regenerate.

Holding down Change or Select does nothing. Pushing Display just says "Customer setting". And holding down Regenerate causes it to do a manual regeneration.