I was a professional breeder and show handler years ago in another life (HAHA). Our breed was German Shepherds but showed all breeds and owned several champion Corgies and Smooth Collies. I never worried about a puppy's ears until after 12 weeks of age and yes they do go up and down when they start teething. One thing you can do is massage the inside of the ear. Have the puppy faceing you, start at the base of the ear, hold the ear between your thumb and several fingers (thumb on the inside, fingers on the back) and then gently rub up towards the tip of the ear. Do this several times to each ear, it helps strengthen the muscles that hold the ear up as well as the cartlidge (sp) and most puppies love it. I did it to both ears at the same time, you can hold the ears up by the tip for a few seconds after the massage so that the ear is used to standing up.
If you have no experience taping ears, I would ask your breeder or vet to show you how. It takes only getting the tape a little too tight to loose the circulation to the ear--it is not worth the loss of an ear if you do it wrong.