How to fix "Media Volume Sync" (Where it is ?)

[auqagg]

This is the question.

My Xperia X Compact – Android 8.0.0 – has lost the feature "Media Volume Sync" with my UE BOOM 3 speaker, but not with my Bose QC 35 headset.

To note :
• My UE BOOM 3 + an iPhone or my computer => Media volume is synchronized.
• My UE BOOM 3 + a Xperia X (no compact) Android 7.0.0 => Media Volume is not synchronized.

• The feature "Media Volume Sync" is not on the three-dot menu icon in the top right corner of the screen on Settings → Bluetooth.

As much as you can, please, use a plain English : I'm a french user.

Thank's for your help and attention.

[pseudonym]

I do not see a "media volume sync" menu item or control anywhere. But I can control the sound volume using the control on all of my Bluetooth speakers and other devices.  I am also using Android 8.0 on my Xperia X Compact.

Perhaps I misunderstand you.