Customise Payslip - Text Box Insert Function

Hi All,

I read from AccountRight user guide on how to add text on a text box in customised payslip template. 

"To add a text field to a form
1 Open the form you want to add text to.
2 In the Customise tab, click Text Box.
3 Click and drag the mouse cursor over the area of the form where
you want the text field to appear.
4 Double-click in the text field and type the text you want to appear."

I tried No. 4 but it won't let me. Please assist.

Siteforce