Sound doesnt work correctly without the OEM Driver and internal speaker is not really a sound system. [URL]   Analog devices windows driver AD198x [URL]    
So I just got this computer from my mom. She sent it to me and said if I could fix it, I could keep it. I fixed it (I just had to reseat the ram) but now the sound is . All the windows sounds work fine (Like the notification sounds and the keyboard clicks in Opera that I haven't turned off yet) but if I watch a YouTube video or something, it sounds all blown out and almost like the background sound is in one ear and louder than the main sound in the other ear. I don't know what caused this. I am using Windows 10 and the Apple earbuds that came with iPhones back when they had a normal headphone jack. 
Sound problems with Optiplex 755