Modifying a symbol in Template Editor
The modifications you make to a symbol in Template Editor do not affect the original symbol but allow you to use the same symbol in different colors, for example. The changes in line and fill properties only affect the transparent parts of the symbol.
If you want to modify the contents of symbol files, you must do it with Symbol Editor.
See also
Adding symbols to a template in Template Editor
Modifying component and object properties in Template Editor