How can I change character back to T-Pose?

When I drag a prefab into scene, it stands in T-Pose. [1.png]

But if I open "Animation" window, and move the red timeline to any other place, [2.png]

the character in the scene will show animation instead of T-Pose [3.png]

and T-Pose will never come back.....

What should I do to change character back to T-Pose?

 

I think you're wanting to click on preview button on the left of the animation window to reset the animation to original state.