The problem is with the Relative Layout, in which EditText fills up the entire available space (in this layout) when text is long enough. As a result it fills also the space that is under those buttons.
You have basically two solutions.
Add a bottom margin to your EditText that will be equal in size to the height of a button.
Use Linear Layout(s) instead of Relative Layout (one Linear Layout to replace the Relative Layout - a vertical one, and another Linear Layout - horizontal - to place those buttons side by side).