It could be about the display mode you select on your laptop, please follow the instruction below to fix it.
If you are using a Windows laptop, please continue the following steps:
1. Press Windows Logo Key + P to open the projection options if you are using a Windows laptop.
2. Select Extend mode to allow your laptop to interpret your projector as a separate device by your laptop.
If you are using a MacBook, please refer to the steps below:
1. Press Fn + C to open Control Center if you are using a MacBook.
2. Click Screen Mirroring, and select Use as Extended Display.
Please be noted that screen resolution and refresh rate will be limited to the resolution and refresh rate supported by both your laptop and projector when duplicate mode or Mirror Built-in Retina Display is selected, if your laptop does not support the resolution and refresh rate you prefer to set on your projector.