Are you using Windows? If so, have RingCentral open and click its icon in the task bar so that it's the active window. Hold down the Windows key and keep tapping the left or right arrow key (while still holding Windows key) until the window cycles around somewhere you can grab it. Drag it somewhere normal (NOT maximized/full screen). Close it. Open it again, it
should now remember where you left it.
Yes I am using Windows. I tried it and then restarted my computer. When I opened the program, it now opened on Toggle Full Screen. When I press that again to get it off, it then goes partially off screen on the top left corner again.