April - Welcome to the forum. Have you just got the car?
If you have recently got the car then you may not be aware about the different signs on the trip computer. The first one you describe sounds like the distance since you last filled up / zeroed the computer. The second one is the anticipated range on the current fuel load. To zero them all press and hold the button on the end of the right hand stick on the steering wheel. To scroll through the different info just press the button.
Hope that helps.
Currently in hugh121's garage: Renault Avantime V6
Insert your key, but dont turn it yet.
Press and hold the trip computer button...
Now, turn your key until dashlights come on...
Leave it to check about 1' then press reset KM/MPH on your dash.
Currently in Untouchable's garage: Megane Coupe 2.0 IDE 16v