Keeping Userforms on top of SDI windows in Excel 2013 and up
With the introduction of Excel 2013, Microsoft changed the windowing of Excel. On all previous versions, Excel had a so-called Multiple Document Interface (MDI), which means all open Excel files are hosted by one Excel application window. Excel 2013 introduced a Single Document Interface, meaning each workbook appears in its own Excel window.
This new feature of Excel causes some trouble with modeless userforms.
This article shows you how to resolve the issues involved.