Hola:
I opened the Text Messaging app and clicked on the top right corner (three dots) and hit Settings. Scroll down to Notifications and Sound just underneath. Change your sound ringtone to whatever you decide.
For email, go into the email app and select the Menu at the Top left and select Settings near the bottom of that list. Select the Email account you wish to change (if you have more than one, you can customize each email account) Scroll down under Notification settings and Choose Ringtone and select whatever sound you want.
That should help you with sounds, and you can also change other apps in this manner. I hope this helps.
Doc