The reading order of slide content is important for anyone using a screen reader. It allows them to hear the content in the order it was meant to be read.
Sometimes you may need to add content to a slide that may affect the slide reading order. Content is read in the order it is added to the slide.
In PowerPoint 2016, you can check the slide reading order by selecting Home > Arrange > Selection Pane. The Selection Pane will appear in the right-hand sidebar.
The items in the Selection Pane are read from the bottom to the top. A good way to remember this is that the Title will appear at the bottom of the list.
To change the reading order, highlight the object and use the up/down arrow buttons to reorder the items.