How to move the Armature Original Point without moving bones? I am a newcomer.

I made an Armature and when I have to use X-Axis Mirror I found my Armature Original Point was not in the middle. It's like this.

So how can I move it to the middle without moving other bones?

Thanks a lot!
Your armature is rotated, maybe it's your problem, you should first unparent the mesh in the Properties panel > Object > Relations, apply its rotation (CtrlA), put its origin at its center, reparent the mesh in the same panel, align it on the armature, and it seems to work better.