How do I make my pose symmetric?

Question

I have already created the armature for this model and they are in the exact positions that I want them to be, so the armature itself doesn't need to be edited. However, the issue is that when using x-axis mirroring, the pose of the armature is not symmetric, like so:

One arm is always in front of the other whenever I try to change the pose. I must have accidentally moved one of the arm bones slightly when changing my rest pose. When I checked edit mode, I identified that the bones that are causing this issue are these bones:

Notice how the positions of the tails of these bones in the rest position are slightly different.

I want to edit the pose so that both arms are extended the same amount when I use x-axis mirroring for moving the pose (in other words, the rest pose should be symmetrical). But how would I do that? When I go into Item > Transform > Rotation for the bones, they both have the same rotation (since I assume they are calculated with respect to their current orientation), and therefore I cannot just copy and paste the coordinates from one side to the other. This is what I mean:

Here the quaternions for both these bones are (1,0,0,0), even though they have different orientations.

I am quite new to Blender, so right now I just don't know how to solve this problem without going through some complicated math or redoing the model. If anyone can provide me some insight into something I'm missing that would be greatly appreciated.

Answer 1

Update: I just found a solution. In pose mode, select the misaligned bone, then go to bone constraint properties and apply the copy rotation bone constraint. Then in the constraint properties, select the armature under the target option, then select the bone you want it to be symmetrical to, and then invert the y and z axes. Then use this tutorial to change the rest pose: https://www.youtube.com/watch?v=iMVs6BP1Q48&ab_channel=Chris%27Tutorials.