Re: Why can't I use backspin/forward spin after the shot is hit?
Whether you can apply post-shot spin will depend on your gameplay settings. If it's an available option to you it should show you what to press at the bottom of the screen once the shot has been hit.
You don't need to use any post-hit spin at all to play the game though. I don't. Club choice, shot type, skill upgrades and loft are all factors in this. The following may be of help:
The Skills You Should Work on NOW - Skills and Shot Types in EA Sports PGA Tour - YouTube