You can edit appearance type items, such as scale and angle as well as flipping it, left/right, top/bottom, changing the default color and line font, but you can't edit the content (add or remove objects).
John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA
It is actually a text that troubles me. Everytime I use the symbols, there comes a default text with it and then I need to delete it. Please see attatchment.
That's the way the symbol was setup. You HAVE to have something in there if you want to be able to change the text upon creating the symbol. If not, then you won't be able to change the text at all.
However, if you find that you're using the SAME text over and over (like A and B or 1 and 2 versus X and Y), then just delete the symbol and recreate it using the text you want as your 'starting' text and save it. You will still be able change it prior to placing the symbol. Creating Custom Symbols is covered quite well in the documentation.