Menus that pull in across different pages require editing separately from the page you may have seen them on.
To do this you need to access the .php file. This can be done through - Appearance - Editor on the left-hand menu at the back end of WordPress.
1) Locate the menu you want to change. The above is the Header, so open Header.php
2) Locate the text you want to change (CTRL+F 'masters')
3) Edit this text (add apostrophe to masters in all visible areas)
4) Click 'update file' in the blue box below the content areas box.
5) Check this has worked across multiple pages that use the menu
Copyright text needs to be updated at the start of every year.
To do this:
Open 'Site Wide Options' from the dashboard left menu and then alter the date in 'Legal Text' field.