Your Captions use Seq fields to do the numbering and identify what goes in the Table of Figures.

Open the field codes in your Captions and change Tableau to Table.

1. Use Ctrl+A to select all the text in your document.
2. Using Alt+F9 (Fn+Alt+F9 on some computers) you can toggle display of field codes.
3. You can use Replace at that point to find all instances of Tableau and replace with Table. (This would also replace Tableau in your text, so be careful.)
4. Remember to toggle the display of field codes back to results when done.

Dealing with Fields in Microsoft Word