Where you start to read a post

Bakers2

This maybe a silly question, and I'm sure someone will say so!   But why is it that when you click on the lastest activity
you fancy reading it will sometimes start at the top, that is the orginal post and other times at the latest post on the subject??

Also there is sometimes a jump to last post button and sometimes not, however many pages the post consists of.

And why when someone likes a comment does it not take you to the liked post immediately?

From reading this forum for awhile I don't really expect to have my points completely clarified but I am interested and puzzled
.