Fuel question

I have a question regarding fuel

When you press the left stick when in flight and click on the white icon to get the fuel menu - you can change left and right fuel to read 100 %

So that when you switch back to external camera view the main display at the bottom of the screen shows 100 % fuel

Noticed that when flying for sometime, the fuel does not go down and stays on 100 % which is a bit unrealistic

Flying in a Cessna 152 with all options set to easy - but with options on easy, I want to change fuel so that it gradually reduces when flying

Any idea how I can do this ?

Thanks

In the assistance options, turn off “Unlimited Fuel”

Thanks - if you have any thoughts my flight sim observations thread - do let me know