So If I can't find my song In youtube Video Editor then what should I do?
Note:I use movie maker to edit my pivot animations...you might say that I can just download the song and put It there But adding both sounds and music Into movie maker will result In Interruptions
This is where my second question comes. Can I mix sounds together with movie maker? and If yes then please show me how :)

You can mix sound effects with Audacity. I'd recommend you use that.

well i always saved it in certain sections. like id save it after adding footsteps, then after hits, then after swings, etc. dont think you can mix sounds together tho (SUCKS)