There are differences in the size of each person's left & right ears and the earmuffs may not fit the ears. You can choose different sizes of earmuffs according to the size of your ear canal, not necessarily a pair of earmuffs, you can choose different sizes of earmuffs for the left and right ears. It is recommended that you insert the earphones into the ear canal and feel comfortable.
Replacement method: Remove the earmuffs from the horn hole, clean the dust in the lower speaker hole, and select the appropriate earmuffs to put on.