You can rename a field in several forms at once
Steps
Select My Apps in the top menu
Scroll across and select Fields
You arrive on the Manage Fields page
Click the title of the field you want to edit
The Edit Field popup appears
Choose whether you want to rename the field on every form it appears in (yellow arrow) or whether you only want to edit it for a specific form (orange arrow)
Rename the field and press Save & Finish
The popup closes and the field is renamed