Can we change the renewal date for a Non-O spouse visa extension in Thailand?

If he hasn't applied for 60-day family extension since he applied for his initial visa for the current extension, he may be able to apply for that and push it around two months later. It depends on your local immigration office policy if these 60 days are added (top-up) to the current stamp or starting on the day of application.

He may be asked why needs to apply for this 60-day extension in-between.

OR he can ask for a shorter period of "up to" 1-year extension when he applies for the next extension. But it's totally the officer's discretion if s/he gives you the length he wants.

If he wants to set a specific date on the expiry date of his extension, he needs to start over the process with a specific procedure starting with a new Non-O visa from the consulate outside Thailand.