Re: How to edit pre existing text.
Reply #3 –
Perhaps the text is part of a different staff? You can usually tell by the colour. The default colour scheme will have the active staff in blue, whilst all other staves are in black. If the text is in black, it belongs to another staff, if it's blue (unless the text colour is changed from default) it belongs to the current staff and you should be able to select (highlight) and edit it.
This can be tricky if you have layered staves and layering is active in the editor ( View | Layering In Edit Mode )