To change your currency  symbol please follow the following steps:

1)  Log into ShopTab admin at http://admin.shoptab.net

2)  Click on Settings tab

3)  Click on Edit Business Info

4)  At bottom of Edit Business Info page select the drop down box and the currency symbol you want to use

5)  Press update and that will immediately update both ShopTab admin and the Facebook page you have ShopTab connected with