Chain always wants to go onto smaller ring

[Ajax Bay]

at the moment my bike is an 11 speed instead of an 18 speed. If gear 18 is Big, smallest then I don't have gears 10 - 16 as the chain wants to always go on the small front chain ring in these gears

The OP has previously revealed that he's got a compact (let's assume 50-34) and a 9 speed cassette (let's assume 12-27). With this setup the gearing overlap (moving from high to low) occurs after the middle sprocket: the 17t. After that 50/19 is the (~) same ratio as 34/13. So the OP's bike (in his terms) has actually 13 or 14 discrete gear ratios. See this link: 50-34 and 9 speed cassette 12-27
The way he has the bike's gears set up is actually doing him a favour (sort of) by dumping off the large chainwheel when he tries shift to the 24t, when he should (good practice) have shifted down to the small chainwheel already. I have already implied that the most likely reason for what he's experiencing is that he's got too short a chain; but the OP has not answered my 'diagnosis question': when static put it on large-large and see what the angle the cage makes. If less than 45o from horizontal the chain's too short.
And the OP say's "I don't have gears 10-16". I suspect that if he rides on his small chainwheel, he will happily progress from the 27t (lowest gear available) right up to the 14t (by which time changing up to the large chainwheel is both sensible and necessary). The gear ratios the OP thinks he's 'missing' are overlaps and available on the small chainring.