Here's how to change innings within the ChangeUp mobile app so that you may move the game along without missing a pitch.
To change innings or switch between home and away teams while tracking pitches for a game within ChangeUp, simply click the "END INNING" button in the lower right corner of the pitch counting screen and then click the Change Sides option.
Alternatively you can click the opposing team tab (Home or Away) at the top of the screen and then attempt to count pitches using the + button. You'll be asked if you'd like to change innings and track pitches for the opposing team; indicate that you would and then change sides.