You can easily edit the text in any of your templates. This includes updating buttons.
Open up the template you wish to change in the template editor.
For guidance on how to access the template editor see here.
Click on any text and type in the new text you want. This works for section headers, line headers and individual blocks.
To edit button options, hover over the option, single-click on the button and then amend the text in a button using the sidebar. Simply click elsewhere to make the change.