If you want more granular control over your hotspot you can enter the values for width, height and X/Y position manually.
- Hover over any screen in your project
- Click Prototype
- Now on your design, click and drag over the area you would like to link to another screen
- Select your hotspot destination in the popup selector at the bottom of the screen
- Click the Coordinates button at the top of the screen
- Enter the values you would like then it enter on your keyboard