You can change legal documents attached to a contract before it is signed:
Go to Settings > Experience Hub > Terms & Conditions.
In the Default Terms & Conditions section, edit the "Contract Terms" or create a new document and then add it here. Add legal documents →
Go to Settings > Operations > Contracts and open a contract type.
In the Documents field, remove the old document and replace it with the updated one.
Click Update.
Note: You cannot change the legal terms of a contract that has already been signed.