Please check the attachment for details.

Instructions 

You can follow these steps to finish the settings:

Step 1: Right click the desktop and left click the NVIDIA control panel

Step 2:  In the opened interface, click Manage 3D settings

Step 3: In the extension interface on the right, click Global settings. Below is a GPU that can be used in preference. Click the drop-down arrow to see the recognizable GPU in the computer.

Step 4: Click Apply in the lower right corner to make it effective.

FYI, The overall process is as follows:

BTW, If you fail to set the NVIDIA graphics card you want as the default even through the above methods. You can also disable other GPUs through the Device Manager to achieve the effect you want.