How can I get louder sound on my LG televisions?

I have two LG flat screen tvs and the sound is so low on the tv speakers that I have to turn the volume up as high as 55 to hear it decently. Also, it doesn't seem to get any louder from 50 to 65 and up. My sister had an issue like this with her television and found a quick solution online. Can anyone help me out?