Most of block titles seems are defined in "messages" file.
 
But not the product blocks.
 
Specially "Product Latest" make no sense in 2 aspects
 
1> The name (title), I want to change to "New Product" or "New Items For Sale" or something like that;
 
2> This block defined as the latest manufactured products based on query on (issue_date), However, in the real life, it should be mean "the new products we just listed/obtained for sale". This I fixed myself by change the SQL query based on Date_added or my latest item_id.
 
But I still not figure out how to change the title, if you know, please help.
 
Thanks.

I just figure it out myself, they are still defined in "messages" file, but in two parts
 
1> PRODUCTS_TITLE
2> LATEST_TITLE.
 
The easiest/best way is to change the html temperate for corresponding block (without affects others).