I have a problem with selecting text or objects in the Viewer

1) I have highlighted text and would like to select the underlying text - not the highlight itself.
2) I have already placed a rectangle annotation on a page and would like to place a text box on top of it but when I click on the area I wish to add more  text  - the  rectangle is selected instead of starting a new text annotation 

 This is caused by the fact that normally the Viewer will always try to select any unlocked and non-flattened annotation and only if there is no existing annotation below your mouse will the mouse click 'action' apply the tool that you have currently selected.

 For a temporary solution you can hold down the Shift key and this will ignore any annotation below your mouse for as long as the Shift key is selected, allowing you start a new annotation. Releasing the shift key will revert back to normal mode and select any annotation that currently exists.

Additionally you could also permanently inverse the way annotations are treated by modifying the Viewer default options. From the main menu inside the Viewer go to Edit -> Preferences -> Commenting and check either or both of the two exclusive mode options available;