There are several reasons a document might be read-only:

• The document is a Backorder document type
• The document has been partially transferred to an invoice in GP
• The document has been locked by another user
• The document is in a batch that is not in the "Queue Access List"*

*The Queue Access List determines who can access a given queue and who sees it as read-only.
To edit the list through the Security Editor module:

1. Go to Modules > Security Editor
2. From the Groups pane, select the Group you want to apply the setting to
3. Select Sales Document Entry from the Security pane
4. In the Misc sub-settings (lower portion of the Security pane), select Queue Access List and open the drop-down list:
   • If the value in the field is an asterisk, none of the list items are read-only
   • If you choose to select certain batches by checking the box in front of them, the system will make the unchecked items read-only
5. Click Save
6. Log out and log back in to see the changes you have made