You want to replace the text ” Copyright © 2013 by DW Argo. Proudly powered by WordPress“, please go to Dashboard >> Appearance >> Editor, find the functions.php file, go to line 116 to 124.

Edit Footer Text
Edit Footer Text

Look at the following screenshot you will find the related posts as shown below:

display related posts
Front-end Appearance

Related Posts “You May Also Like” will display all the posts that have the same tags, that’s why when create post, make sure you put same tags from them.

Back-end Settings