Sounds like you are using mobile mode on your PC? You should be able to click on the units within the circle and get them selected.
It might work better if you zoom in or zoom out, I forget which one is better.
While that works I would really recommend using the actual desktop mode for a better experience with a mouse and keyboard. You should be able to open the menu in the lower right corner, then click the settings gear. If you scroll down in that menu you will find a "switch to desktop button"
In some cases that doesn't work for one reason or another, so you can clear the cookies in your browser that are from Callofwar.com. This will require you to log in again, so be sure you know your username and password. This will definitely have you back in desktop mode, and will also reset a few things like hints about the game features.
