After inserting the symbol you have created, select it and then right click on it and select Explode.
Do the same procedure again.
Then you will be able to adjust different parts of the symbol, in your example to rotate the text.
Another way is to avoid use text at your symbol at all and then add a label on the symbol and assign the rotation to 0.
Finally, if you don't add text in your symbol, you can add one with the draw text tool.