Setting graphic styles for symbols affect all elements in that symbol, including text. I need it to stay as it is. Is there a way to protect some elements (text, in my case) from being altered by graphic styles?
Not by applying styles to the symbols themselves. THe entire purpose of symbols is that they are identical elements.
You can duplicate a symbol, edit the specific internal elements and apply styles to those. Then use that new symbol.
You would need a separate symbol for each different internal appearance.