Your table is running past the 1 or 1.2 inch margins but is not large enough to require making the page landscape
Turn on the Ruler
Click on Table
A small grid pox appears on the ruler at the top of the page you can then adjust the width of the columns in the table
If that doesn't work and your table continues to revert to the original size you will need to go to Table > Properties > Options turn off Automatically resize to fit contents
