LCD TV-DVD combo sound echoes and I can't find the setting. Do you know how to fix it?

Question

LCD- TV/DVD combo; bought 3 months ago..went out already. Polaroid repaired it with new part, but now the TV "echoes" and it didn't before. No setting appears to control it. I tried switching it back to factory settings and it didn't work. When TV 1st powered up after the guy fixed it, I saw him scroll through a menu and he selected this setting. But now I can't find it.