- Disable "Use the Print screen key" in Accessibility-Keyboard.
- Go to Lightshot's options by right-clicking on the lightshot icon in the taskbar
- Reassign the PrintScreen key by unchecking-rechecking the "General Hotkey" icon then pressing PrntSc while in the white input box.
To do so, click in the box, then Press the print screen key, then click OK.