How do I stop teams from turning my headset volume up to 100% in the "App volume and device preferences" before each call?

I have the same issue too, using Jabra2 evolve 85.

Having the same device my volume always jumps up when the headset switches from normal mode to call mode. I fixed it by prioritizing the computer audio. This is a setting in your headset which can be set with Jabra Direct software in: Settings =>Softphone => enable Prioritize computer audio.

I have two fixes; I have only employed the first one.

1. Use a microphone and speaker (either built-in or external). I value my hearing more than my privacy on work teams calls. Sorry everyone else around...
2. use some kind of external audio interface that allows you to control levels after the software-controlled levels on your computer. This costs something and involves another box outside your computer that you have to haul around. I haven't done this for Teams, but I do some sound recording / reinforcement work and this would work.

I have the same issue too, using Jabra2 evolve 85.

Same issue as all of the above, new calls are always at 100% and if we leave a call and then go back to it the volume also goes back to 100%.

But also noticed a new hiccup, when we join the Teams call we used to be able to drag the Teams app volume down to 0 if we needed to grab an IRL web phone call using the same headset (wired, not wireless or Bluetooth, and using the 3.5mm jack, not USB). As of this week when myself or my coworkers drag the volume down to 0 with the system volume at 100 we still hear teams audio as if it was at level 15-20 previously. The only person NOT having this issue is the one using her speakers for the Teams call rather than a headset since her Bluetooth headset will only accept one input, either Webcall or Teams, without muting her. The one bonus to her dog chewing the wired headset's cable.

It happens here as welll.
I use a bluetooth earphone (Samsung buds 2). Whenever I enter a call, Teams increase the volume to 100% without asking anything.

I have to right-click on Windows' volume icon and "Open sound settings", where I see "master volume" set to 1% (this is Windows' volume).
But scrolling down to "Advanced sound options" and clicking it, I always see "Microsoft Teams" set to 100%. I have to decrease this to 20% or less every blessed time I enter a call.
This is really annoying.

This is not a Windows problem, nor a earphone problem, since we can see that the setting that keeps going to 100% is in "App Volume".