I’m not sure about what you are exactly asking. I have an old version (2000) of MS project so the caveat here is that things may have changed. Given that, you can think of all fields including custom fields as being columns in either an underlying task table or resource table. If you think of them as tables in an underlying database, the tables and all the columns including the custom columns are always there. So when you build the custom fields, they will continue to exist in the underlying tables. When you want to see the custom fields you simply have to add them into whatever view you want that is available. So if you create a custom field in Gantt view it will be available for any other view.
There are some limitations and it can be tricky to use custom fields but this is the basic idea. Continue to post and let me know if this answers your question.