Oxygen portable concentrator settings

Not sure that I understand the problem. If the machine is still operating, it should just be a matter of turning it off then on and pressing the volume (liters per minute) button to the correct output setting. I'm assuming that the battery is charged, or you are using household A/C.

I'm afraid I can only give advice for the machine I use, so without knowing what we are talking about, my input is limited.

It might be a good idea to take your device to a local Durable Medical Equipment supplier for a check up?