I'd see about locating the correct remote control somewhere. In the meantime, while playing the desired source, turning the program knob on the receiver should cycle it through the different sound modes until you get to the desired mode. If you cannot change modes, make sure Straight mode is off by pressing the button on the receiver next to the Program knob. With it off, you should be able to change sound modes. However, according to Yamaha, this model cannot change the sound field program for Dolby TrueHD, Dolby Digital+, DTS HD or anything higher than 96kHz. So, you would need to convert the signal to PCM from the source and then you can change the sound program in the Yamaha to achieve multichannel stereo modes.