Usually it's a dial or lever that raises & lowers the wheels on the bottom. It should have an indicator to show up/down or high/low or 1234. If it doesn't have a height adjustment it will cause excessive wear on carpet. Usually it's a dial or lever that raises & lowers the wheels on the bottom. It should have an indicator to show up/down or high/low or 1234. If it doesn't have a height adjustment it will cause excessive wear on carpet.