how do you fast forward on the apple tv remote?

Which model do you have?

On a Siri remote:

Rewind or fast forward

You can move rapidly forward or back through video in several ways. During playback, do any of the following:

• Preview video on the playback timeline: Press the Play/Pause button or press the Touch surface to pause playback, then swipe left or right on the Touch surface to move back or forward in time. A small preview window shows the current scene. Press the Touch surface again to start playback at the new position or press the MENU button to cancel and resume playback at the original position.
• Skip back or forward 10 seconds: Press the left or right side of the Touch surface to skip back or forward. Press again to skip another 10 seconds.
• Rewind or fast-forward continuously: Press and hold the left or right side of the Touch surface to rewind or fast forward. Release to resume playback.

• Use your Siri Remote with your Apple TV - Apple Support
• Use your Apple Remote (aluminum) with your Apple TV - Apple Support