How to reset back camera position?

I changed the player's camera CFrame so the player can see the whole map, but after a few seconds i want it to change back to its "original" CFrame.

I figured out its "original" CFrame by getting the cam position when i'm in test mode but now the camera is stuck on that CFrame and won't move.

local cam = workspace.CurrentCamera

cam.CFrame = CFrame.new(10,50,75)
wait(3)
cam.CFrame = CFrame. new(-39.986, 15.408, 10.988)

This must be in a Local Script:

local cam = (workspace.CurrentCamera);
local char = (workspace:FindFirstChild(game.Players.LocalPlayer.Name));

cam.CFrame = CFrame.new(10,50,75);
wait(3);
cam.CameraSubject = (char:FindFirstChild("Humanoid"));
cam.CameraType = Enum.CameraType.Custom;

wait();
script:Destroy();