I can't move all bones at once by editing the Transform value, only by Grabbing

See gif. I want to move the seat along the global X axis, which I can do by selecting all its bones and doing G & restrain. But when I type the same apparent value into the Transform tab manually, still with all the bones selected, only the bottom bone moves. What’s the deal-i-o? What am I missing here?

EDIT: I notice that when I select the connected bones in Object mode, I can do what I’m talking about. And it also shows the transformation in the tab as an X axis transformation, as opposed to Y for some reason when I’m in Pose mode.

Gif is showing a file not found.

When you enter data into fields manually, it only affects the active selection. If you want to apply to all selections, right click in the field (like a translate X field) and choose “copy to selected.” Note that if the other objects already have a location, this will replace their location, not offset it.

With multiple bones selected in pose mode, Alt-click in the field for the value you want to change (X translation, in this case) and type the desired value.

This is true for most cases in Blender, when you want to input a value for multiple selections, be it transforms, material colors and values, modifier values (as long as they share modifiers) and so on. One exception to this is in the case of constraints. But in most other cases it works.

As for why it shows the value for X axis in object mode, and Y axis in pose mode, that most likely has to do with the way your bones are oriented. The transform boxes show local coordinates.

I hope that helped. Cheers!