Re-mapping On Screen Keyboard in DOSBOX Pure?

[TPR]

I feel like I should know how to do this, but I'm pulling my hair out trying to figure this one out.

Right now the On-screen keyboard for DOSBOX Pure is mapped to the keyboard #3 key. How do I change this to another key that isn't more often pressed?

When I go into controller mapping, I see this:

So I can see that it shows my SELECT button brings it up, which is fine, but then also the number 3 key. When I press either of them I get this:

I've gone into the RetroArch settings and tried to re-map both the On-Screen Keyboard (which is not mapped to num 3 in the main input settings) and I've also tried to re-map the "Escape key" which is mapped to num 3 in the input settings.

I can actually get the Escape Key to re-map (I used TAB for example) and that worked, but then when I tried to save core overrides, it went right back to being num 3, even without restarting the core.

Let's say I wanted to re-map that onscreen keyboard to the TAB key, how would I do that and make it stick?

And yes, I know I can use Game Focus mode as well, but not all games need that, and right now the number 3 key is the only one really getting in my way.

As always... thank you in advance for the help.