From the "Quick Start Guide", that can be downloaded at "Digital Gadgets" site the developer, manufacturer and marketer of this Sylvania device, in the "Getting Started" section following the steps in item 3 will calibrate the screen.
3. CONFIGURE TOUCH SCREEN
1. Press the MENU button on the back of the product.
2. Tap Settings on the bottom menu.
3. Scroll down and tap Touch Screen Calibrate
4.Use the stylus to tap the middle of the displayed crosshairs to calibrate the touch screen. Note: After a system reset, it may be necessary to recalibrate your screen.
As noted in their guide, you can do a "system reset" by placing the tip of your stylus in the hole on the back marked "Reset".