Read-Only field in forms sharepoint

Here is the default view of an task list form without the read-only field:

1. Open your list in SharePoint Designer. The fastest way is like in the following picture.

2. Create a new form.

3. I created a new form for new entries / items / tasks (be sure to give it a new name e.g. “CustomNewForm”, set it as a “newForm” and set it as default)

4. Open the newly created form in advanced mode. (just right click onto the form and then … advanced mode)

5. Now look for you field (in this case “Priority”) and the important part here is the ControlMode. This is set to “new” (because of the newForm).

6. Change those two values from “New” to “Display” and save the form.

After that, if you create a new entry / item / task in your list, the priority field should be read-only.

And that is all you have to do. Of course you can do this with every other field. It depends only on the ControlMode of each column.