How to change volume / microphone in voice calls, can't hear

[Guy_]

When an incoming call appears on the watch,

• tap green answer to start a conversation
• tap red end call to reject the call

If you click answer,

• tap speaker [top right] to adjust the volume, if you can't hear the other person well
• tap microphone [bottom right] to unmute if the other person can't hear you, [or mute]
• tap three dots to switch between call on phone or watch
• tap red end call to end conversation

if you tapped volume,

• adjust the volume with multiple taps on + or -
• adjust for each new call [setting not remembered]
• swipe right to get back to call screen

if you tapped 3 dots,

• tap to switch between call on watch [keypad] or on phone
• swipe right to get back to call screen

See also How do I take on-wrist phone calls with my Fitbit smartwatch? 

[Clove6060]

@Guy_ 

After terminating a call where volume was increased  does the volume return to a specified level?  Will it stay at the adjusted level from the previous call or must the volume level be adjusted for each call?

[Guy_]

@Clove6060  - it resets to the default for the watch and will need to be adjusted for each call, if necessary.