Hello,
the string added to the URL is based on how the menu leading to mosets-tree component is named. So if you create a menu item named "My tree", the URL will be:
mysite.xy/my-tree/category1
If you do not access the component from the main menu, the default component name is used and this cannot be simply customized.
If you already used the component with the default name, it is possible, the URLs are already generated and they will not change automatically if you rename the menu item. You will need to purge all URLs or at least those related to mosets-tree to see the change.
Best regards,
ARTIO Support Team