When updating Corona versions it really should respect the previous system settings, or at least give you the option to Retain or do a "Clean" install. This is one such setting that we always forget to put back to 1.0, as one example.
And at any rate, Corona should really be defaulting IR scaling to 1.0 and not 2.0 anyway. Anything that results in lower quality (blurry IR) surely should never be the default. Give users the option to increase this to 2.0 or whatever they want if they have slow IR with their system. But we have requested this many times over the years so... :)