How can I create a 3 user filled form?

I have a requirement where the rural agent (RA) first fills certain fields on the form. The rest of the fields in the form are read only for the RA. This form is then seen by the Support Agent (SA) who, based on details filled in by the RA, adds his comments in the fields provided. Lastly, the QA sees the data filled in by the RA and SA and adds his comments. This completed form is now viewable (read only) on our website for all three users .

Please advice how I need to go about this.

It seems to me that you primarily want to create a sort of approval form with certain read-only fields which can be reviewed and finalized between three parties before submission.

First you'll want to refer to https://www.jotform.com/help/194-How-to-assign-a-status-to-submissions and set your form up similar to that.

Additionally, you'll want to use either a text area or the text field and mark it as read only. If you choose the text area for inputting html that is already read only but you won't be able to add anything to it unless you go into the formbuilder to modify it. 

And lastly, I would recommend adding and using a preview widget which basically shows a reviewable section that is read-only before finalizing to submit.

If you are confused and feel like you'll need more help just start building your form with the fields you want and we'll help you more to guide you along.