Hi welce to FA how you can make your anim go back and forward is to go to settings and look at the bottom of the menu and see the past and past back click　the one you want to put back and make sure to look at your drawing if its going back of forward when you done click the save on the top of you anim on the left and also click the title if you want to name your drawing and if you want to download your drawing for other ppl to draw on to go to the settings again and look at the top of the menu and you see the red arroe pointing down and click it if you want to continue the drawing click the green arrow pointing up and thats it thanncc you if you skiped the impotant part good luck doing it your own.