My Ruffles gets brown waxy buildup in her ears too, which frequently creates a yeast infection. Part of it is due to the fact that her roommate Flurry loves to lick her ears! My vet has me do a 14-day run of Momentamax (available from your vet) once a day and that clears it up. It's a creamy liquid that goes in easily and you don't need much so she tolerates it if I'm quick getting it in.
For infections, my vet has also done one-time treatment at the office and repeats in two weeks that really knocks out problems quickly. We don't like to use that except for more serious infections though.
I personally hate the ear cleaners commonly sold that you have to pour in the dog's ears and make a real mess of them and everything around them. I use
these wipes, twist them up, and insert into the ear to clean as far down as I can. Much less messy and the dogs don't mind it as much either.