Price layout

Hi can someone help me please. My prices are set GBP but the price separator (decimal point) is showing as a comma at the moment and needs to be a fullstop as i am working in £ please can someone tell me how i get my prices to show as fullstop and not a comma i have attached a screen shot to explain what i mean thanks

Hi,

Go in the menu System->Currencies, edit your currency and change the decimal separator option.