Nop4.2, Set default title, the all category, product page add it, if can't set, the home page title is empty. Please help how to fix this?
From your post it's not very clear which are the exact elements you can't set.
In general all titles and text elements are manageable through the administration of your website. Some are set via string resources and are a part of your language pack, others are set in the catalog administration, or topics administration, etc. The "home page text" title for example is set in the topics administration.
Please refer to the nopCommerce documentation for more detailed information.