The phone keyboard does not support arrow keys for scrolling, and I can understand why. It sounds like a really backwards feature when you can simply tap a word; any word, and a text cursor pops up. You can then grab the text cursor by tapping and dragging it around. If you're trying to insert the cursor in the middle of a word, it's oft easier to just tap the word (so the entire word highlights), and browse the suggestions that pop up. If none of the suggestions are correct, it'd be faster to hit backspace to delete the word, and type it out again.