An individual cell within a table acts just like any other text box as far as its content or even appearance is concerned. Therefore, all text alignment options used for text containers work with table cells too with a few exceptions.
To learn more, choose your version of PowerPoint. If we do not have a tutorial for your version of PowerPoint, explore the version closest to the one you use.
Microsoft Windows
Text Alignment within Table Cells in PowerPoint 2013
Apple Mac
Text Alignment within Table Cells in PowerPoint 2011
