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.
Settings--General settings --- SEO---Default page title
Page title SEO adjustment: Store name comes after page name
Page title separator
Default meta keywords
Default meta description
If I set default page title, all page will add it in the title in the end, if leave it empty, the home page meta title is empty.