After some testing we found that:
Sennheiser headsets can be controlled with the volume settings on MS Teams. Other ways to adjust the volume is on the headset itself and in the computer sound settings outside of the MS Teams program
Leitner headsets can not be controlled with volume settings in MS Teams. The only way to adjust your incoming audio is by using the “+” button on the headset (for wireless). Adjusting the microphone under the base will not make a difference either.