how to save special character in soapUI

Dear All,
is there a way to save the special character in soapUI?
for example: i add a little sequare thing(hexadecimal) in front of text,although the first time is right when i copy the special character to soapUI, if i save the soapUI project and then reopen, the special character will be changed into question mark (?), i do hope people here can give me a hand?? how to save the special character in soapUI?

ps: i try to change the setting regarding font, it seems works badly as well.

thanks in advance