Unpotty training yourselfSet the Texting App as the Default the First Time You Launch It. Open the app and click past the initial startup stuff (here, we have to click "Start Using Textra" and agree to the necessary permissions). Once the app launches, you'll see a button at the bottom asking if you want to make it your default app. Tap the button, and then tap ...Middle passage worksheet pdfTap on SMS Disabled. Readers must note that this option of using Signal as your default SMS/MMS app is only available to Android users. "In addition to supporting end-to-end encrypted messages and calls with other Signal users, Signal Android can be configured as your default SMS/MMS app," says Signal in its support pages.