How to fix large conchal bowls?

David Furnas MD a plastic surgeon in Sacremento, California described a procedure for fixing prominent concha. The basic technique is to set it back with a stitch or remove a portion of it prior to stitching it back.

I would recommend seeking an in person consultation. If your ears don't protrude but your ear buds fall out, the likely issue is that your ear canals are large. Earbuds are usually retained by the ear canal as opposed to the bowl of the ear. If the issue truly is your ear canal you would benefit most from custom fit earbuds as intentional narrowing of the ear canal will likely only create serious medical issues. I hope this information is helpful for you.Stephen Weber MD, FACSDenver Facial Plastic Surgeon

And otoplasty is what you need to reduce the conchal bowls. If your antihelical folds are not well developed they can be narrowed as well. See a lot of very experienced surgeon who does natural looking ears  for the best possible result.

If you had prominent ears, a large conchal bowl could be made smaller minimally invasively, without incisions and extractions of cartilage, by the so-called medialisation of the antihelix with the help of the so-called stitch method. However, as you report that your ears aren’t prominent, this is only possible through incisions and extractions of cartilage from the conchal bowl with the traditional method.

It is possible to reduce the external ear and conchal bowls and it will involve scars which may or may not be noticeable.