Steem Post few issues !!

Guys !! I have few question about Steemit Post Please clear my mind

1. How people get earn fast with steem post ? (if you say getting upvote on the post then check this out )
   For Example :
   He got 39 upvote and 23 comments his steem dollar calculated 1.22 $

where in other side , he got 28 upvote and 6 comment he got 7.27 steem dollar

Why this happened .. ??? i felt Upvote does not count !!!

1. Why steem dollar decrease time by time in old steem post?

suppose : i post some content and i got 10.45 steem dollar but day by day when i upvote to other post or not i should say i stop reading and posting steem post my steem dollar on the my particulars post keep decreasing day by day !

Hope you understand what i mean !

Please clear my mind why this happened !