If the special character you need isn't in the Symbol dialog box, you can try using the 'Advanced Symbol' option or creating a custom symbol. To access the 'Advanced Symbol' dialog box, click on the 'Symbol' button and select 'More Symbols'. From there, you can select different fonts or search for specific characters using the 'Subset' drop-down menu. Alternatively, you can create a custom symbol by drawing it using the 'Insert Shapes' menu.