Problem:
How can I prevent that only Post Authors can access the update form?
Solution:
Go to the Toolset → Access Control page and click the Toolset Forms tab and click to expand the "Post Forms Front-end access group" and find your form name and adjust the permissions to "Edit Own" and save the permissions (you should revoke the "Edit Others" permissions).
Problem:
Possible to change data type of a custom field?
Solution:
To change the data type of your custom field, you should navigate to:
=> Toolset => Custom Fields => Edit your custom field group that holds your desired field => change the Field Type to "Single Line" for the field for which you want to change the data type and save the custom field group.
