I could see some templates in the config folder of my server installation ...KNIME Server 4.7\workflow_repository\config as webportalTemplate.goldMining webportalTemplate.default
Is this where I can make some changes for Menus and individual quick form pages. ?
That’s the right place to look. Renaming the directory to webportalTemplate and restarting the server will apply the changes. I’d recommend applying the goldMining template to get an idea of what is possible, and probably deriving your changes from the default template (which is just applying the same template as you have currently).
Full details of the available options are part of the admin guide (see page 29 onwards):