As we experienced some data loss, due to the Exit - button (next to the Back - button), we thought you may wish to consider the following suggestions.
Please let me know, if these need a feature request:
Exit: Not clear that the collected data will be deleted upon pressing the button. Re-titling it to "Discard & Exit" (or something relevant) would be more transparent.
Back: Not clear that going back to the previous page(s) is possible. For usability / UI-compatibility reasons with LimeSurvey, adding a back button would be nice.