Are there any suggestions on how can I make minor editorial changes across a magazine all in one go?
As a magazine editor, I have to republish a magazine after making minor modifications across the magazine.
It would be helpful to know what kind of changes you are talking about. If you mean changes to the layout, you are going to need to have access to the program that allows you to work on the entire spread of the magazine. If it is to be a "uniform look" my suggestion would be to do this by yourself. If you have several people contributing to a layout issue, likely you will find the issue is not resolved with everyone's contributed changes.
If you mean editorial changes to stories, however, especially simple grammar/proofreading issues, you could probably have an intern or associate work on it for you. If this is a school magazine of which you are the supervising teacher, you should choose one of your brightest students for such a task. Likely, you will still have to read over it, but hopefully most (if not all) small mistakes will be caught.
As I reread your question, I'm wondering if part of the solution you seek is how to combine all contributions into a similar format/program. Before you begin to do any editing, if I were you, I'd have all your contributors send you their work electronically in a standard program like Microsoft Word or Works. This way, also, you can simply open everything in one place and work through each.
Scan the pages of magazines and upload them at www.onlinedocumentconversion.com ; download editable version within minutes Once you have editable version you can make those changes in word.