hi all' thanks for the answers. i have a one problem with chainging a tempo with audio snap. when i need to change any part of the imported file i don't know how to do this. i pressed on the keystroke that do any changes in a tempo ctrl+shift+t and it's says that i must active the tempo tollbar that locates in the view menu. i skipped this and i went directly to the insert menu and then i pressed on this to check if it works. then i pressed on comma to select this track' and f9 to select by time in sonar. when i went to the part that i wanted to change til this i pressed on the spacebar to stop this and pressed f10 the thru time that ends my selection at this time. i enabled the audio snap before this actions by f12. and enabled the button that follow project tempo by alt+f12. why this doesn' work? thanks for answer!