First, LPChip is correct that the top slider is the master slider and, generally, for most applications, this will control all volumes. However...
A relatively recent development in various meeting software products is that their audio is separated from the overall system volume controls, and the result is that, sometimes, only their own application volume controls will control their volume.
The reason for this exemption is not to make meeting volume control more annoying and complicated, but to allow meeting audio to run in and out over a device separate from the system audio (the RESULT of this exemption is definitely that volume control in a meeting IS more annoying and complicated). Your master volume slider controls the volume of a specific selected audio device. You can change this device using he controls in the taskbar.
The Fix
The general rule to get meeting applications such as Teams or Zoom to "obey" the system master audio volume is to make sure that your systems' main audio output and the meeting software audio output devices are the same.