Font does not look good at 50pts and above

Hi, in contrast to most people having trouble making their fonts look good in small size, my problem is my font is aliasing when it is in a large size. The original set of font has nice and smooth edges, I merely edited the dollar sign and the at sign, and the font is now aliasing. I am not sure if that has to do with hinting? From what I read, hinting only has something to with making the font looks good in a small size. I know editing any of the characters or copy and paste anything into the font set would eliminate the hinting information. My font actually looks good in small size, it only start aliasing once go past 52pts or so. If this has to do with hinting, then I guess I have no luck in fixing that.

Does your font have greyscale values set? If not, try that on the format menu.