How to change Vin (input voltage) on rlc_gui simulator?

Hello! I'm using the rlc_gui simulator, activated by entering in the function window: 'rlc_gui'. I've managed to change the circuit components by changing the simulator code. now i want to change Vin (input voltage). how can I do that? the simulator code, is accessible by entering in the function window: 'edit rlc_gui' the code is also attached.