By default, table columns are not fixed and when you enter content, they start to move around and be directed by the text or images that are being added. You are able to fix a column's width by setting the pixel or percent specifications. We recommend that unless you are a web designer that you stick with "percent" as it is an easier concept to grasp. This means that the column will always be a certain percentage of the table's full width, no matter what device or screen size is being used to view it.
Click on cell from the table that you want to adjust the width.
A set of controllers will appear, select the last one "Cell properties"
The cell properties dialog appears and here, under "Dimensions" you can make the necessary adjustment to the column width
An easier option is to place the cursor of your mouse in the edge of the column you want to resize and slide it to the left to decrease the width or to the right to increase it. The adjustment is automatically saved.