It could be a setting your using or it could be just an error (did you try saving other things as a .png to see if the same thing happens?). If it keeps doing it repeatedly, I suggest finding a free [img type here] to .png image converter. That way, you save as a .jpg (or whatever filetype is requisite) and convert it to .png. If that doesn't work, then try to find somebody that can save it as a .png without it turning the blue hue. If none of that works, then I'm sorry to say, but your s.o.l.