As explained, many times already on the forum, the Addon Manager DOES NOT apply ANY tweaks on its own.
Those tweaks you see are those you ALREADY had in your FSX.CFG!! They are being read from there, and presented AS THEY WERE, just to allow you to edit them in an easier way.
If you didn't had a specific tweak to begin with, the value shown there is the default value which is used by FSX anyway even if there's no tweak so, saying "I don't use them any more", it's not really relevant, since FSX has an internal default (which is what is shown on the Addon Manager) which is used even if you *remove* that tweak manually from the FSX.CFG.
If you change them, they are NOT applied or saved, unless YOU press the "Save to FSX" button