My older lab suffered for years from yeast infections. We tried ear canal flushes, antibiotics, maintenance Epi Otic and also Oti Clens and the apple cider vinegar/alcohol rinse. They all worked for awhile but never totally cleared the infections up.
It all came down to a food allergy.
Now that he's on a grain free diet, EVO large bites & a dollop of the 95% Evo Venison on top he's not had a recurrence in years. I also give him grain free treats.
It may cost more for the food, but in the long run of all the vet visits and aftercare, it's far less than I used to spend.
With this food, they eat less and it's utilized more as well.
There are several grain free foods out there. Just try it for 6 weeks and see if it doesn't help. That's the usual time for any kind of dietary help, especially elimination diets, to show the complete results.
It is true that the long eared breeds are going to be more prone to yeast infections/bacterial infections...specially if they go in and out of water a lot as well.