You can use the Highlight Text tool, Strikethrough Text tool, and the Underline Text tool to mark up text in PDF.
1. Open a PDF in OfficeSuite.
2. Switch to the Review tab.
3. Select your option: Highlight, Strikethrough, or Underline.
4. Drag over text to perform the action.
*Note that you can also change the color. To do that, tap Color and pick or create a custom one from the expandable bottom sheet.