aspect ratio & crop settings help

[alpinestars69]

ok i am not fully understanding what is up with the aspect ratio & crop adjustments. in the drop down for these video adjustments i have them set to how i want the video to play in & on maybe the next video i will have to repeat the adjustment process to the same settings again. is there a way to have ALL files open to the same settings? and what does "lock aspect ratio" actually mean??