Q. I am using comparison table shortcode but configured values like currency prefix, no of decimals, hide decimal symbol are not working.
A. Some of templates have design constraints and will ignore some of configured values. for example templates with decimals are shown at top will not show decimal symbol even if selected. Only template that will honor all the selected configurations is default template (i.e. when you choose no template).
Q. I have changed my product description but it is not visible in price slider.
After making any changes in WHMCS you should sync data with WHMpress using settings page.