We're sorry about the trouble with Photoshop. Would you mind sharing the version of Photoshop you're using? Are you using a desktop or a laptop? If you're using the app on a Windows desktop, are both monitors connected to the display outputs of your graphics card?
Please ensure you have all available Windows updates installed on the computer along with the latest drivers for your computers graphics card. You can try disabling the option to Use Graphics Processor from Photoshop by going to Preferences, then Performance. Once done, quit & relaunch Photoshop to check if that helps.