The behind-the-ear hearing aids are kept in place by an earmold, a piece of plastic that is put into your ear canal and holds them firmly in place.
Many individuals who use behind-the-ear hearing aids struggle to maintain them in their ears, but there are solutions available.
Selecting a pair with an adjustable stem, which can be made shorter or longer depending on how deep your ears are, is one way to go about it.
A solid seal between your skin and the end of the tube where it enters your ear canal is another approach to prevent them from slipping out.