we have made some changes, after logging out, it reset to the original view. I was told there should be a Save button, but cannot find it anywhere
This should help you. If you are adding columns to an existing view (System for example) the changes you have made on the view are temporary and will be lost if you navigate to another view without saving them.
community.dynamics.com/.../dynamics-365-column-options-feature-to-add-view-columns-on-the-fly