I take it it's an MS181?
They can be tricky to start. Get the pop on full choke, then switch to half choke, start her up with the chainbrake off and let it burble a bit. Hold it with the handle between your legs when starting- this is the accepted safe way to start a saw. You'd fail your saw test for doing it with the chainbrake off, but it's that's bollocks anyway. Mechanical aptitude should overule some bloody chair polisher who's never done more than fell a couple of trees before becoming an assessor.
After a few seconds blip the throttle repeatedly. Yes, you sound like you're a prick pretending you're on Axemen, but this get her going without giving it wide open throttle long enough for her to bog down. After a few seconds of this you should be able to hold it wide open for a good few sconds whilst muttering 'come on you bitch' as she clears her throat. I always feel bad doing this on a cold saw but technically the oil is there (in the fuel) and it's the only way to get it to run right from the off.
Don't mess with the low screw if it's a new saw- it's very unlikely to need it and all you'll achieve is the chain running by itself due to a high idle once warmed up. You could try screwing it in a smidge if you really want, but as you say, they are fine once warmed up- there's just a knack to it.