Why can't I change the email signature for my Exchange email accounts on Galaxy S6?

[AC Question]

I recently got a Galaxy S6 and have 2 different Exchange email accounts set up on it using the stock email app. I have changed the signatures on both accounts to include company name, address, etc. But, when I go to compose an email from either account, the signature remains "Sent from my Samsung Galaxy smartphone". Why won't the new signatures appear? Is there a line limit? I am in Ontario Canada, on the Telus network.

Thanks!