This normally occurs if you are using the Win7 Streamer. Here are some suggestions for you to try:
1. Use the "native resolution" of the computer. To change the screen resolution setting, tap the Splashtop icon in your tablet or phone's Home screen to display the list of computers that have been added. Tap the arrow button to the right of the desired computer name in the list, then change the resolution as desired.
2. If you are using the Aero theme, the "Custom DPI setting" option will be enabled. Please check the current value and try to select different scaling sizes, i.e. 100%, 125%, or 150%, to see if there is any difference.
3. If you are not using the Aero theme, the "Custom DPI setting" option will be disabled, but you can still try to change the scaling size to see if there is any difference. Generally, 100% or 125% should be good for Splashtop Remote.
NOTE: You can verify whether or not you are using the Aero Theme via the Control Panel:
Control Panel > Appearance and Personalization > Personalization
There will be 3 options (as below) and you will see which one you are using:
- My themes
- Aero themes
- Basic and High Contrast themes
You can find more information at this topic: