Once you have created a symbol from a palette, it is
very simple to change its properties.
To edit a symbol from a palette:
You can either
double-click in the tree view, or
click the edit symbol button on the tree view toolbar.
This will display a property sheet where you can modify
the symbol parameters, according to the way they have been defined
in the palette, but also change their coordinates on the map or their
SDM ID.