but I would like it so when the player clicks 1 button it turn to this colour (39, 181, 255) and the 1 that’s not selected turns to this grey (130, 130, 130)
Inside the function you can reference the active and inactive buttons since you know which one is being pressed, and color them accordingly. For example, the fov70 button event’s code could include:
Fov.fov70.BackgroundColor3 = Color3.fromRGB(39, 181, 255)--set fov70 buttons' color to indicate its active
Fov.fov50.BackgroundColor3 = Color3.fromRGB(130, 130, 130)--set the other button's color to indicate its inactive