The Selection options in Documents offer a convenient way to select any part of the content or the entire content (text, images, etc), after which you can manage it per your choice.
Select all content
1. Open a Documents file.
2. Click the Edit Tab and choose Select All.
Select a part of the document
1. Open a Documents file.
2. Left-click and drag to increase/decrease selection.
Select whole paragraph
1. Open a Documents file.
2. Triple click on a word to select the entire paragraph that contains the selected word.