Hi Paige
Edit - just opened your file...I noticed that the first quiz question doesn't have a submit button selected it's had a trigger to use the next button - but that doesn't explain why the properties disappears...
If you are on the latest version I would submit a case with Articulate support and get them to have a look at it. Sorry I couldn't be more help
I'm not seeing that behaviour. Have you tried closing your file and reopening? The slide properties window isn't detaching itself and floating somewhere else? If so, try View > Redock all windows
