There actually is not an "override" command for changing Domains because the setting of the Domains is one of the most influential decisions you can make in creating a storyform. If you cannot change the Domains you have set for your Main and Influence Characters, then too many other appreciations are set in your storyform to allow them to be changed. All of the appreciations are linked together by complex relationships which limit how easily they can be changed. If you are telling a story about a Main Character who is primarily seen in terms of his physical activities, that is a completely different kind of story than one about a Main Character who is seen primarily in terms of their Psychological manipulations of others. As a result, changing a storyform from reflecting one kind of story to reflecting another involves changing many appreciations beyond just the MC Domain.
The best place to make this kind of change is in the Story Engine, which displays the most essential Objective Story appreciations and the most essential MC appreciations all in one window. In the Story Engine, beside each appreciation, is a little box that is supposed to look a little like a pad-lock. Click on these boxes next to the appreciations that you know are set the way you want them to be in your story (for example: Resolve, Outcome, Judgment, OS Domain--whatever you are sure is right). Then use the button to the right of the screen called "clear." This will clear all of the appreciations except for what is held in place by the locks you have set. At that point, you can use these pull down menus to select what you really want.
This can be more complicated than it sounds though. You may not realize the impact of all the selections which you locked. For example, Approach (Do-er/Be-er) and Mental Sex (Problem-Solving Style) can have a strong impact on what MC Domains are available. Direction (Start/Stop) can too. These appreciations are also easily misinterpreted in stories, so you may have accidentally selected the opposite of what is most appropriate for your story. I recommend double checking the definitions of these appreciations and reading about their impact under the "Background" buttons in the DQS to make sure you set them the way you want to.
Another thing you should know is that you can't lock selections in the Story Engine which are in italics. You must first select them yourself and make them appear in regular type before you can lock them. Do this by simply clicking on them with your mouse.
It sounds like you have a good grip on how you see your Objective and Relationship Story in Dramatica because you want to swap the Main and Influence Character Domains. Since these two characters represent the opposing sides of the story's central issue, it can be easy to be selecting appreciations for one when it turns out you are really describing the other. Remember that the Main Character presents the first person view of what it feels like to be in your story while the Influence Character is always felt by their impact on the Main Character (and thus, by the audience). We ARE the Main Character, while we WATCH the Influence Character and feel their influence.