The difficulty went up 8x, so the reward went down 8x. I don't see where you're confused.
so we will mining more to get less ?
Correct. That is what happens when the difficulty retargets with all crypto-coins. It's just far more drastic in the first month or so of a coin's existance.
and how to make that work in 7 threads instead of 8
If you're on windows I've answered this more comprehensively somewhere in this thread, but hit ctrl-shift-escape, select processess, right click on POOL_MINER.exe, select "set affinity" and uncheck one of your cores.