The animated characters start moving, all tough i ve changed just the hand IK

Hello, i ve gone through the animation tutorials of UMotion, and i ve started my first animation, which is a simple handshake, BUT, after i ve created and applyed the animation to the animation controller, i ve noticed that the characters start moving, which i don t understand whyMovie_007.mp4
Also, how do i control the FK/IK, from what i know, IK gives a position (used for a grabbing animation for example) and FK used for setting a position (a walking animation)
To clarify the main question, what should i do to map and keyframe JUST the hand animation, without changing the the player positon? And for creating a walking animation, what is the best way to create a walking animation (keyframing the positions and rotations), are there any tricks?