Selective potty use - what to do?

For the last few weeks,my LO has had several times each day where he has taken himself to his potty.We always praise and reward with stickers,and he seems really proud of himself. However,we’ve hit a snag as there are lots of times during the day where I take him to his potty (or ask him to go) and he will scream and cry and refuse.We’ve tried reminding him of his stickers,and even saying that we’ll only play a certain game/ read a certain book after he’s used the potty but no use. I’m against “forcing” him and turning it into a negative experience,but I also want to reinforce the idea that we use the potty all the time,not some of the time.Any thoughts? We haven’t got in hard with the no nappies/ no trousers at the moment as we have a newborn and so would struggle to juggle the mess! Thanks