The oil indicator is very low and when I speed up it goes up when I slow down it goes down and the chek gauges light comes up. It has plenty of oil how can I fix it

First thing you need to do is have the actual pressure verified by attaching a mechanical oil pressure gauge in place of the sending unit on your engine. If the gauge verifies your dash readings then you have an oil pressure loss inside the engine that needs further diagnosis (worn bearings, obstructed pump pickup etc). If pressure drops enough to turn the light on I would not drive it 'till you know exactly what's happening inside or you can and will have an engine failure.
One warning...if after you remove the pan, you find that the pump screen is not obstructed, Don't blame the pump for the low pressure.....check the bearings. However, regardless of what you find (obstruction or worn bearings) it is advisable to replace the pump. Pumps generally don't fail but ingesting debris (carbon or metal from bearings) will either score or wear the pump housing and vanes enough so that the pump will never reach full pressure.
If the external gauge shows normal pressure, contrary to what the dash gauge tells you, blow out the sender passageway and replace the sender, then add marvel oil at each oil change as it will help dissolve any crud accumulated inside the oil system.