Hi Jordyn,
- Is Windows 8.1 activated?
- What is the make and model of the computer?
- Do you get the lock screen preview when you lock Windows 8.1?
- Do you get any error message when you try to change the lock screen?
Please check if Windows 8.1 is shown as activated.
a. From Charms bar, click Settings, Change PC settings.
b. Press PC & Devices, click **PC info.**Now, check if the Windows is activated.
Please provide us more information to help you better.