Saved phrases are sentences that you sent previously and that you saved to save time. You can only send saved phrases from the Android or iOS app. Simply go on the profile of the user you wish to send a saved phrase to. Under his username, tap the chat icon, then tap on the third icon under the message box, select your phrase, then tap the SEND button.
To add a sentence to your saved phrases, simply type a phrase and send it to someone. Then tap and hold the phrase you just sent. Upon tapping that phrase, you will be given the option to Copy the phrase or to Save Phrase. Tap Save Phrase.
To edit your saved phrases, still in that third icon screen, tap on EDIT. On that next screen, you will be able to delete saved phrases by clicking the garbage can or even add new ones at the bottom. Just write your sentence and click ADD. Make sure to click the Save button on the top right corner of your screen after any changes.