Check out this JBL In-Ear Fit Guide video, or read the below article.

In-Ear Fit Guide

A proper fit is the most important thing when using in-ear headphones (wired, wireless, TWS). Without a solid, tight fit the headphones will sound thin (lacking bass), not very loud, and will do a poor job of blocking out unwanted sounds.

In-ears, unlike an earbud design, are meant to be pushed into your ear canal, creating a tight seal. If this seal is not accomplished, you will not experience good results.

1. Typically speaking, the medium sized ear tip is already installed on your in-ear headphones. If it feels tight or loose, try the other sizes.
2. As you try each ear tip, rotate forward and/or back until you create a tight seal as seen here.
   NOTE: The image shows a stick style in-ear, but this applies to any in-ear design.
3. As you are twisting and pushing you will hear the sound quality changing. When you accomplish a tight seal, you’ll hear it. You will have more bass than in any other position, and the leakage from outside noise will be minimized before ever turning on Noise Cancelling (if your headphones have Noise Cancelling).
4. If you have one of our headphones that uses the JBL Headphones App, check in the app to see if there is a “Check My Best Fit” banner. This feature will walk you through getting the best fit and will let you know when you’ve accomplished it.

While this may seem a bit daunting, after doing this a few times, inserting the in-ear headphones into your ears and getting a good fit will become second nature and will take a second or two each time, not minutes. But it is definitely worth spending the few moments the first time around, in order to get the most out of your in-ears.