Buy some Assos chamois creme. Apply liberally pre-ride, apply lightly post-ride.

Get some high-end bib shorts or shorts. Not the sort of junk that some bf'ers think is high-end, but actual high-end stuff: $200+ for bibs, $150+ for shorts. Assos is a good brand, but the higher-priced options from Specialized, Giordana, and a few other mfrs are good, too. Make sure they fit properly, which is very snug.

Practice good hygiene. Shower ASAP after getting off the bike, especially hot weather. (Sweat is your enemy.)

If the above doesn't fix the problem, make sure your bike fit is good, then perhaps try a new saddle.