Question Menu [home page] Default Menu Item choose [Recent topics] different

  If I just have "one" Kunena menu，I can  set for both the same, it's ok.

But , not, there are "many" Kunena menus in my site, but configuration just one setting,  how could I set for the

Maybe First kunena menus will show Forum1,  Second kunena menus will show Forum2

Hope you can understand what I mean, thanks!

This is not a problem. I thought at first that you generally want to link to forum 1.
You can completely override this setting in the configuration by linking the menu items Alias directly to the tabs.

1. Go to the main menu  and open the Menu Item Alias.
2. Click on Clear  

3. Select now on this place, the Kunena menu item Recent Topics
4. Go to the Kunena menu item Recent Topics and choose what you want (either show all or a single category)

Now you can select in all your other Kunena menu items like Forum 1, Forum 2 and so on what should be displayed. The different selections working now for all this menu items regardless of the configuration.