Can't Get To Proper Window To Type in Product Key For Activation

[cw34]

So I installed Windows 10 via media creation tool on my newly built desktop PC but its stating my windows key is from what I'm assuming the laptop I made it from ( GF's laptop). I bought a key for windows 10 but I can't get to any screen that allows me to type it in. When I go to System> Activate I get a notification sound like a window popped up and needs me to click something but I can't see anything nor is a window present. From there the whole settings window freezes up and forces me to end it. I can't find anyone with this specific problem for a solution. Is there any way to remedy this without reinstalling all my programs? ( :[ )

 

[The_Prophecy]

Open the Run box by pressing Windows + R on your keyboard. Type the command "slui.exe 3" without quotes.

 

[cw34]

Open the Run box by pressing Windows + R on your keyboard. Type the command "slui.exe 3" without quotes.

Thank you so much, got it working!