Welcome to the lmms forums Mass.
I hope I understand your question.
So here's what to do:
Right click on the BPM number eg. 140
Then select remove song-global automation.
That should take care, of the BPM resetting problem.
Tell us if it works now.
Welcome to the lmms forums Mass.
Yep Brandy is correct. You get this kind of issues, when you import midi-notes. They (can) have 'build-in' features that ned to be removed.