Spacing not allowing to go below 129! How to fix?

What do you mean ‘accordingly’? I want the LSB to be -600, just as it is.But want to reduce the right hand one to less than 129. Is it not possible?

I also realise now that my solution for this problem might lie in kerning triplets, so that might solve it a better way and perhaps this is wrong thinking of mine above. Just having trouble with that issue as the only tutorial I can find is from 2013 and doesn’t seem to apply to the current version. That thread is here: