Click on your SETTINGS App. (Question: YES or NO, is your's on the first page/stack also?)
Then click on: GENERAL > KEYBOARD > SHORTCUTS > + Sign > Then ADD your phrase and shortcut.
Here's my example: My phrase is: "If you have any questions or concerns regarding the above, please let me know." My shortcut is QZ. Typing that at the end of emails is a rather tiring task.
Now all I have to do is type my shortcut, which in this case is QZ, then hit the space bar and...
VOILA! 14 words instantly in 3 keystrokes (Q-Z-Spacebar) Very helpful with different number of signatures for multiple email accounts.