There are two primary adjustments for the derailleur for smooth shifts - just went through this with mine, a brand new explore+3.
1. There is a screw adjust for how close the top tensioner roller sits from the cassette gear/ring(s) - it should be as close as possible on all gears but not touching. So take a look, mine was sitting way low and wouldn't up-shift worth a darn. Clunky, mis-shifting, changing gears when pedaling, beyond annoying.
2. Next, peer down vertically over your chain as it aligns to any gear at the bottom of the ring as the chain enters with the derailleur - it should line up exactly with the chain ring. If it's one way or the other, left or right, adjust the cable length (I think it's deraileur end on the Diore) so that it aligns perfectly. Some shifters have a cable adjust ferule as well for fine tuning.
You should get perfect shifting now.
And yes, the yammer drive does not have a gearshift cut off so you need to back off on the pedal pressure to shift, then resume.