How to add a new row of just one column, below another row of 3 columns?

Question

How do I add another row of just one column below another of 3 columns? In the image below I have tried to add a row below the 3 column row but it added a 3 column row instead of 1 and I am unable to make it a 1 column row.

Thanks in advance.

Solution

You can merge the cells generated below the row to make it a single column. To do this just select the three cells, right click and select merge cells.