This article will show you the setting where you can adjust the window (time) for adding a signer to a completed form.
Follow these steps to edit the "Add Signers Window":
Step 1: Click on "My Account Details" from the left side menu
Step 2: Click the edit icon beside "Company Details"
Step 3: Under "Form Settings" you will find the "Add Signers Window (Hours)". Enter the amount of hours you would like to keep the form open to adding additional signers.
This setting is set to 24 hours by default.
You can increase this to whatever number of hours you want. If you change this to outside the threshold of when your Form was created you will be able to go back and add a signer, until that threshold is hit again (ie. if you increase it to 48hrs, you will be able to change yesterday's Form today, but not tomorrow).