There are two extremes of thermal contact our gas can have with its surroundings:
In complete thermal contact with surroundings (which are at a temperature controlled by the temperature slider) it shows isothermal (constant temperature) behaviour through changes of volume and pressure.
In complete thermal insulation from its surroundings (no heat flowing in or out) it shows adiabatic behaviour - the temperature changes that occur as the gas expands or is compressed are not dissapated by heat exchange with the surroundings.
As you experiment with the gas under adiabatic conditions, you'll notice that adiabatic changes are only reversible if you make changes very, very, slowly. Any faster and the gas will heat up over cycles of expansion and contraction. Why?
What is temperature?
Why does a gas heat up when compressed and cool as it expands?
Are systems in the real world either isothermal or adiabatic?