Hmm how come the potential stats of Monster book arnt upgrading when your book lvls

Switch sets and your monster book lvl will go back to the lvl you had it.

I am not talking about the stats o fthe book lol. Not talking about the +1/2/3/4/etc all stats on the book itself. I know those lvls up. Mine is +6 already and lvl 6. What i am talking about is the set bonus itself where it gives you potential stats. Such as hobpq which at lvl 1 it is 1% all stats and 15% ignore. Each book lvl according to the chart white provided is suppose to also lvl up the set bonus. At lvl 6 book you are suppose to have +6 all stat and 3% all stats/15% ignore def for the bonus. However, my set bonus and I assume everyone elses as well the set bonus doesnt lvl up with the book stats? I know that's confusing but I hope i explained it better this time.

@above so should i just stick with 1% all stats and 15% ignore der rather then 2% attack from dead mine set?