Someone help me! I think timing problem? :p

Note: grammar is bad (sorry -.- )!

New to makeing songs in step mania! Made one which I think it oh ok. Making a new one now although timing is oh ok. When play from the start of the song but timing is out of place if play in the middle of the song. Any suggestion for helping plz. Thank you.
:D
:3

Hi! Sounds like the BPM is incorrect.
If the timing is OK at the start but the arrows are too late in the middle, your BPM is too slow and needs to be increased.
If the timing is OK at the start but the arrows are too early in the middle, your BPM is too fast and needs to be decreased.

You can use a program such as FL Studio or a tap tempo thingy to help you determine the exact BPM of the song.
That should be a start, let me know if it helps!

This actually sounds like the variable bit rate mp3 problem. Reencode the music to ogg with audacity or something.