Pi hole will not block youtube ads. You have something else doing that.
The thread you linked is old. Since then youtube have started delivering adds as part of the stream.
They can be blocked with fancy software and scripting tools but not via DNS based blocking (pihole) as this would just block the video as well.
I would imagine that most of your devices have browser based add blocking stuff instaled but your android device does not.
The solution in that (old) thread was also that the pihole was not being used as the DNS.
The easiest way to use pihole is to have everything in your house connect directly to your router.
Setup your router so that its primary dns is your pihole and its secondary DNS is anything else (google or opendns etc).
Then with the pihole config, you pick the dns it will use (google or opendns etc).
You pick a secondary dns (google or opendns etc).
Then you grab some block lists and whitelist some important stuff.
If you are super bothered about getting 100% add blocking do not set the secondary DNS on your router (or also set it to the pihole),
but you will loose your internet if your pie dies, is rebooting or your devices refuse to use the PI hole IP as a DNS.
PI-Hole is designed to be run on every model of the PI and it will work in all cases but your mileage will vary depending on what model you have and how lucky your purchase was.
Not all pies are created equaly.
The brand / spec of SD card you run off has a massive impact with some dieing within days.
Lots of the older pies cannot cope with the throughput, over heat and lockup.
A zero will work fine as long as you are not doing anything else heavy with the pie.
The newer PIEs will happily run raspbian, kodi, torrent client and pihole all at the same time, just do not use the SD card for storage. Get a USB disk or something.
a lot of the older pies do not like using ethernet and USB at the same time. It slows down, heats up and dies.