Previous button - to the previous slide in the sequence of slides or the last slide visited?

I second the motion to have the Previous button go to the previous slide in the SEQUENCE, not the one that was visited. As someone noted earlier, browsing training material is not the same as browsing the internet. 

Please let us easily change this option rather than forcing us do the laborious task of programming each and every slide. Some of our videos are close to 100 slides!

Thanks in advance.