I pressed J to move my anchor point of an image, but now I am stuck in that mode, how do I go back to position changing mode?
The move tool is assigned to the V key. For anything beyond that quick tip you have to provide proper system and version information.
The shortcut to move anchor point is Y not J but that's neither her nor there. To get back to position changing mode first select the selection tool. It's the little arrow to the left of the little hand on the top menu bar. If you hover your mouse over it it will tell what the short cut for it is. Second: Maybe go through some basic tutorials on how to use After Effects. After Effects CC tutorials | Learn how to use After Effects CC
Thank you so much! I really appreciate it, and yes, the shortcut is Y. May I ask what you do? Once again, Thanks a ton!