First of all, log into your Settled home companion.
Then click 'Adverts' in the left menu.
You should then see a large thumbnail of your ad. Click this.
Select 'Asking Price' in the left menu before updating the asking price and the price type.
Click 'Save' for your changes to be applied to your ad. Any updates will take around 24 hours to be shown on Rightmove or Zoopla.