there are universal plastic glues that have solvents and a combination of plastic materials. i don't think it works as good as specific glues which have solvents and that particular plastic; there are glues specific to PVC, CPVC and ABS (also there are variations for pressure ratings and setting time of concern to plumbers, likely only one of each type in general stores).
plastic hardware is strange stuff. some plastics have a property of being deformable, the types used for hardware are. after a nut has come tight it may stretch the bolt a whole lot, a number of turns. also these deformable plastics (if not stretched to the breaking point) can then relax and go back to closer to their original shape. also plastics are slick, often used as a sleeve bearing with metal because of this, can be though of as self lubricating. you can then turn a nut on an assembly tight and keep turning it (as the bolt stretches and with little resistance) and then if you stop before it breaks you can then watch then nut unscrew itself (as the bolt relaxes and shrinks and turns the nut with little resistance). makes you think you have a screw loose (that was punny).
plastic hardware works where it doesn't have to be real tight or you use some thread locking mechanism.