This issue just jammed me up and I think it's a terrible UI design to include the "Screens" operation under "View Field Configuration" when that operation applies to ALL field configurations across all schemes without any warning. We're using the Enterprise Edition and setup a number of unique projects and configurations and I was shocked to find out that in the process of removing screens from one of my configurations that I had copied that I disabled functionality in my other projects.

In my example I had the following setup:
------------
Field Configuration Schemes:

• Issue Reporting 1 --> Project 1
• Issue Reporting 2 --> Project 2

Field Configuration:

• Issue Screen 1
• Issue Screen 2

Screens:

• Enter Issue 1 --> Project 1
• Assign Issue 1 --> Project 1
• Enter Issue 2 --> Project 2
• Assign Issue 2 --> Project 2

Field Configuration Issue Screen 1:

• Assignee -->
• Enter Issue 1
• Assign Issue 1
• Enter Issue 2
• Assign Issue 2

• Description -->
• Enter Issue 1
• Assign Issue 1
• Enter Issue 2
• Assign Issue 2

Field Configuration Issue Screen 2 (copied of Issue Screen 1):

• Assignee -->
• Enter Issue 1
• Assign Issue 1
• Enter Issue 2
• Assign Issue 2

• Description -->
• Enter Issue 1
• Assign Issue 1
• Enter Issue 2
• Assign Issue 2
  ------------

I then went and removed the Assignee and Description from the "Enter Issue 1" and "Assign Issue 1" screens in "Field Configuration Issue Screen 2" and ended up losing all those fields in "Project 1" which uses "Enter Issue 1" and "Assign Issue 1". Had I seen some sort of warning in bold-red font that I was about to change ALL of my projects, or better yet – if this action was not even permitted here, I would have never done this. Putting a note in the documentation is not good enough, you need to have a warning in the UI because it's definitely not clear that you're changing all your projects..... why bother to have separate configuration areas if it's going to affect everything? The only thing you see on the "Associate field XXXXXX to screens" page is: "Associate the field XXXXXX to the appropriate screens. You must associate a field to a screen before it will be displayed. New fields will be added to the end of a tab." No warning at all....

To me it sounds like this UI works good for the non- Enterprise Edition of Jira, which does not allow multiple Field Configurations, and it was just left as is for the Enterprise Edition where it's definitely not sufficient.