bike999

im bike newbie and im trying to adjust the gears and made sure the high and low gear limit screws were adjust properly but when i try to index the gears of the rear derailer every time i go and down it slips and clicks when i pedal.its a px 6.0 mtb that is a week new.
i have to ask too that when im doing the adjustment of the gears of the 18 gear bike that when im trying to adjust the cable tension with the barrel of the rear derailer that with the high first 3 gears they work but when i go back down they slip and click
and was wonder is there a certain front gear you have to be on too? huge thanks in advance!

FBinNY 

The limit screws are exactly what the name implies. They set the outer limits of the travel range, but that's all they do. Picture a 6 lane road with Jersey barriers on both sides. Moving the limits would b like moving the barriers, but it's still up to the driver to drive the lanes.

The actual shifting and centering on sprockets (trim) is set by the cable, and fine tuned with the adjusting barrel.

Tere are plenty of good tutorials out there, both text & photo and video. Review a few until you have a good sense of the job before actually starting.

One hint that may save time. Every mechanic has his own way, but I prefer to set the limits first, and test by shifting, not with the lever, but by pulling the bare wire away from the frame. You want the loosest settings that still 100% reliably prevent overshifting and dumping the chain over the sprocket.

Also, if you do everything by the book, and still have issues, it could be a bent hanger. Experienced mechanics usually check this first.