Hi anowarmolla55,
Could you tell us your firmware version?
Please also make sure that you have updated to the latest firmware version.
If the problem is still appearing, please tell us the app name and versions that this problem happens in.
When this problem appears, are you using earphones/ phone's speaker/ bluetooth?
For earphones and bluetooth, please tell us the brands and models of them.
Please also show us a screenshot of your volume level when you feel the volume is too low.
Thank you 🙂