1. Enter the reading page and tap the zoom tool in the bottom toolbar -> Click Zoom in / Zoom out to adjust the size;
2. Or click the numerical box in the bottom toolbar -> Pick the number you need or hit Actual Size / Fit Width / Fit Page to choose the appropriate size according to your needs;
3. Or right click any area in the PDF tab, then select Resize Page and choose Actual Size / Fit Width / Fit Page to meet your requirements;
4. Or press Ctrl + scroll the mouse wheel, you can also zoom the page;
5. Or double touch the trackpad of your laptop to change the magnification;
6. Or choose Settings on the upper toolbar, and find the Default Setting in the File Attributes -> Fit page as default when opening documents to select Actual Size / Fit Width / Fit Page -> Apply your settings.
7. When you're in full-screen mode, you can only change the size by pressing Ctrl + scroll the mouse wheel or double touching the trackpad.
Note: If the page size is still not suitable after zooming in or out, please check the size of your original PDF document.