This may sound silly, but my picture went very poor after moving things around in my home.
I had put my cordless landline charger/..handset right next to my router and had awful picture.
Seperating them by a foot brought picture quality back to what it was before.
Mayb a coincidence, but worked for me !!!
This is the Roku section, so your question may get a better reply in the correct now TV section ( white box/black box/smart box)
One likly issue could be poor wifi, have you tried changing the settings on your router? try an app such as wifi scan on your phone.
There is a Roku speed test app/channel that should alert you to poor wifi ( not sure if its in the now side of things)
another option would be to connect via ethernet, if the now box's support this
also se this answer on page 1 of this thread, but as mentioned you may be better asking in the relevant now tv box sub forum
Thanks for your post and welcome to the forum. Like most providers, NOW TV uses adaptive bitrates, this can't be overidden and aims to give you the best quality picture your connection can support. If you're experiencing fluctuations in quality, a wired connection to your box is always preferable to wireless.
Just signed up for the 2 week trial
i am using LG and Samsung tv, both hardwired to the BT fibre router
also have a chrome cast
all 3 systems suffer pixelation problems with NOW
however all three will stream BBC HD, amazon and Netflix without problems
such a disappointment , not sure this is worth the money
So the NOW TV app is constantly dropping - PC via app, white box, xbox one. ALL other services run fine including Amazon Prime, Netflix and Iplayer. Not to mention the DL speeds I get on xbox one at 60mbs. Speed is fine so please do not even mention that as I have 130MB routwer speed with various speeds throughout devices ranging 60mbs - 100mbs with ping level at around 14/15. EVERYTHING WORKS but NOW TV. Sky need to sort this now or I will also be cancelling. Watching football the other week with my Dad and I was actual apologising to him for my poor picture quality and buffering - not good enough.