As a “newbie user”, less than 1 week of using SDRplay I was also very confused about the interaction of ZIF and other mode settings that effect the display and the ability to control Sample rate. I would suggest that the software just “grey out” those input boxes rather that eliminate them entirely from the display window. That would be much less confusing and more in line with typical “windows programming protocols”. If they were greyed out then the tool tip “hint” could prompt the user about the various interactions when he mouses over the greyed out area.
some of use that use this software on an occasional basis and might be away from it for a month or two will forget these things that a “professional user” who interacts with the software on a daily and continuous basis will have committed to “muscle memory”. SDRplay has a decidedly “industrial feel” to its user interface, which is fine, but there are trade offs with that. Because of wide acceptance of the excellent product into a very diverse range of users it might be worth thinking about having the developers run the user interface by some windows developers that are familiar with following the