how do I watch my cameras on my desktop computer?
You can use the eufy web to watch
You can install an Android emulator like Bluestacks if you are running a Windows or Mac PC. Once you have the emulator installed, download the Eufy Android app and run it in the emulator. I have been using Bluestacks on a windows PC with a 32" monitor for several years now.
There are some ads when you first start Bluestacks, but once it switches to the Eufy app, it works just like your phone or tablet.
I am using the older V4 version as the PC is running Win 8.1. If you are on win 10 or 11, you will need to install Bluestacks v5.