What kind of liner is it? Overlap, beaded, j-hook/unibead? Also what is your pool brand? Some of them have very specific/different specs (Doughboy, Lomart, Esther Williams, et) than other pools. You should double check the liner delivered to be sure that it is the appropriate size for your pool type and size - you would be surprised at how many times an error can be made and the wrong size or type is picked up or provided. Any pictures you can post regarding the issues you are having will help a lot.
First off, your liner should only be installed on a sunny day, warmer than 70 degrees. This can mean the difference between a stiff, obstinate liner and one that is as pliable as melted butter that you can move around and will stretch so nicely into your pool. When installing a liner, you will often find, depending on pool type and liner type, that the liner may seem to be "snug" at the walls and especially curves of an oval while filling. If properly fitted and installed on a warm sunny day, the liner will stretch in properly and should be just right once you get about 10" or so below the skimmer/returns so you can then cut them in. You may wish to secure the walls on the sides and curves with padded clips or bracing until the water reaches over a foot or so and the liner has stretched appropriately into the bottom.