I found a videos on youtube but everything is with older versions and they seems more simpler to me..
See screenshoot below, so dynamic fee is checked and when slider is on the left side it show this.
http://prntscr.com/e77ed1I think that i send this transactions with same settings and how you can see, it's very very slow :/
AHA! 25 blocks is the minimum that you can get it to (I think based on the app).
Slide it to the the other side and it should make your transaction much faster (you want it to be within the first 5 blocks - around 50 minutes). More expensive to put it in the first block and people expect transactions to take about that time to confirm normally sometimes.