I can't modify styles
- The styles sidebar deck is displayed using ▸ or F11.
- The cell styles are selected and displayed.
- A right click on a style name allows you to choose Modify, but the corresponding dialog does not appear.
A sheet (the one in question or another) is protected by the menu▸ .
This protection is naturally extended to the modification of styles. All you need to do is deactivate (temporarily if necessary) the protection of these sheets in order to modify the styles.