Every time I connect my Bluetooth headset, the volume is set to max.

AI Overview
To fix the Bluetooth headset volume resetting to high on Ubuntu 24.04, which uses PipeWire rather than PulseAudio (hence no
default.pa), disable absolute volume for Bluetooth devices. Edit /etc/bluetooth/main.conf, set Experimental = true, and add MultiProfile=multiple under [General].
Steps to Fix High Volume Reset:

Edit Bluetooth Configuration:
Open terminal and run:
sudo nano /etc/bluetooth/main.conf
Enable Experimental Features:
Locate the [General] section and add or change the following line (if it has a # at the beginning, remove it):
Experimental = true
Add Profile Support:
In the same [General] section, add:
MultiProfile=multiple
Save and Exit: Press Ctrl+O, Enter, then Ctrl+X.
Restart Bluetooth:
sudo systemctl restart bluetooth
Reconnect Headset: Disconnect and reconnect your Bluetooth headset.

This allows PipeWire to handle volume correctly, preventing it from defaulting to maximum.

I followed the instructions, but still, when I connect my Bluetooth headset the sound is set at 100%. I set the volume at 50% and ran sudo systemctl restart Bluetooth. Now when I connect, the volume is preset at 50%. I do not know if editing the main.conf file was necessary, but the volume is working as I want, so I will leave as is. “Do not fix what is not broken.” 😉