Audio output vs. headphone.

If the volume is already maxed out on your Bluetooth headphones and the Bluetooth transmitter/your computer, then it won’t get any louder.

An awesome Bluetooth headphone:

https://www.audio-technica.com/en-ca/ath-dsr9bt

Above is the best Bluetooth headphone I’ve heard. Interesting tech, and many of ATs other BT headphones are great too.

If you only want to spend a little, go for Jabra or Jam Bluetooth headphones.

For sound problems on your computer, run the audio troubleshooter.

Thank you for your advice. I will clarify.1) I use the same blue-tooth on the same PC with a USB blue-tooth dongle and it is loud enough.2) I use small Creative audio system with 3.5 jack on the same green socket and it is loud enough.3) I hear almost nothing once I plug-in the Aluratek device.4) I guess that altogether is because the Creative has an amplifier inside and the headphone does have (if) only a limited amplifier.
... you may be right and there is no way to fix if. I was dreaming about adding some other small item between the green socket (OR USB port) and the Aluratek blue-tooth transmitter (many headphones connect to USB).-----------------------My actual desire was a bit different. I want to have two pairs of headphones connected to PC so that may watch a movie together with my wife.

Sounds like everything works except the Aluratek module, seems like it’s the culprit.

Actually their support advised to return the device to the store to take another one. I did only 1/2 of that.
Unfortunately that looks to be the only device with the features I want on the market.