When you have a selection of information, Calc should be clever enough to automatically determine you want to find & replace within that selection.
It should also be very easy to correct that assumption if you have highlighted cells, but want to find & replace in the entire document.
- Highlight information
- CTRL F (find and replace)
- The 'advanced options' UI is expanded
- Only in current selection is automatically checked
- Since advanced options is expanded, you can really easily uncheck 'current selection only'