Editing containers and categories messes up links to content

Forgive me if i can't describe things within Drupal terminology: i'm new at this.

i'm finding that when i edit a container and/or a category, afterwards unforeseen things happen.

For one, i've edited the menu titles of the categories and containers to be different from the titles of the container/categories themselves (real titles are long and descriptive, menu titles short and easy to read), and once i save a container, it and all the children have their menu titles reverted to the actual titles and not the shortened ones. The only place i can change things back is to go into admin/build/menu and reedit the menu titles. This can be quite tedious to redo when there're a lot of children.

For another, once in a while, but eventually almost always, if i edit the containers or categories often enough the content nodes that use the category disappear from the category's node page, even though the content node itself still has that category selected. The only way i've been able to add it back into the category node display is to create another content node and paste the previous content into it.