Combination of Mixamo Animation Causes Crossed Arms?

I rigged this character mixamo itself and uploaded in blender. Now trying to combine animations from mixamo to the rigged character but the arms are crossing

Hi, check the rest pose of each rig they need to be the same pose.

one is T pose and the other is A pose
so what to do now ?

That is the reason. you need to re pose your character and target again.

i mean how can i change the rest pose ?

You re pose it in pose mode. and Apply pose as rest pose.

Thanks a lot