To change the basic fields (the ones at the top) you go to https://middleware.idxbroker.com/mgmt/pages and on the line of the page you want to edit, click on the Edit link under the Preferences column, then go to the “Search Setup” tab and there you can hide/show the fields you want and set the default values for any fields.
For the Advanced fields (the ones at the bottom), click on the Fields link under the Customize column. There, you select the property type you want to change the fields and then on the “View Settings” button. You will then see the fields below. There you can set the default values, change how the field will look, add new fields, remove and move any fields.