kerning problems

[Eshbal]

Hello,

I use font made by someone else and I try to improve its kerning. After selecting the pairs of letters, aligning them, and clicking apply and OK, nothing happens. I saved the file of course and exported it. I removed the previous file and even changed the fonts properties. But neither in the preview nor in any other external program (such as Word or InDesign) nothing changes, and the kerning looks exactly the same as before.
I would appreciate any help.

Thanks,
Eshbal