Most problems are one of the six below. If yours isn't here, send us a message and we will come back to you.
Check the output picker is set to the headphones or sound card you are actually using, and that the headphone mix fader is up. On a phone, take it off silent.
Raise the input gain until the meter sits around the middle when you talk normally, and switch processing to medium so quiet passages lift.
That is the microphone hearing the speakers. Put headphones on at both ends — it clears instantly.
Usually a weak mobile signal. Stand still, avoid busy public wifi, and reconnect — the app will pick the link back up.
Turn on the keep-awake switch in the app and use full screen mode. That stops the screen sleeping during a broadcast.
Make sure you are signed in with the same email you paid with, then reload. Your access lives with the account, not the device.
Tell us what you were doing, what device you were on and what you heard, and we will get you on air.