Personal:
Tap the hamburger icon in the upper left hand corner. Click "View Profile." Tap the pencil icon in the upper right hand corner. Here, you can update: name, birthday, weight, height, and gender.
Fitness:
From the Today tab, tap the sliders in the upper left hand corner, tap Edit preferences. Move through the series of questions to update your workout preferences and equipment access. But updating, your plan will be more suited to your current status.