So, a project can have multiple worksheets with overlapping content (i.e., models that exist in multiple worksheets). Changing a worksheet can affect other worksheets after saving the change in order to keep consistency (this happens automatically). You can save a (selected) worksheet to the project using the confirm button (the icon is a hook/check symbol) in the tool bar.
After saving the worksheet, the project will be marked as changed and can be saved using {{key press|Ctrl}} + {{key press|S}} or the save symbol in the tool bar, when the project page is selected.
=== Project models ===