Hello Rob, can you explain more about why you can't edit text? You should be able to click into a text box, highlight the letters and make any changes.
If you click the text layer in the layer stack that will highlight the whole text box, so you can change everything easily. If you're using a template and having trouble clicking on a text box because it is behind something else, then use the layer stack on the right.
Click the text layer then press enter on your keyboard, which gets you into the text editing box.
Use Shift and the keyboard arrows to highlight the letters and make your edits.
Click anywhere away from that layer to commit the edits.
Here's a video about selecting objects that are behind each other where text is dealt with from 1m43s