I have a simple table. I want to add arrows inbetween the numbers in the table, however everytime I try to move an arrow inside the table, it gets moved down below the table immediately!

If the arrow is a graphic (rather than a special character), try formatting it as inline (right click, Wrap Text) and then pasting it.

That didn't work.

I don't know the size of the arrow you are trying to insert into the table but, you can try inserting an arrow via the INSERT ribbon in the "symbol" section on the far right. When you click "symbol" a drop-down menu will appear. If you cannot find the arrow, you can enter the Character Code of 2190 through 2195 from the UNICODE (hex) character set to select a right, left, up, down and a combo up/down arrow. If these arrows are too small, you can adjust the font size for the arrow to increase the size.

If the arrow is crossing cell borders, inline will not work. Try drawing it and setting it to be in front of text. This is going to be a mess for editing so do it late in the writing process.