Here are all important links:
viewtopic.php?f=1&t=4740
-A few rules and useful forum instructions
That is because of a MIDI-file you have imported. They have hidden information.
Right-clock the BPM-gadget, and in the context-menu select 'Remove-global-automation'
If it does not solve your problem, do write back with your:
* Name of your Operative System (Windows/ Linux/ Mac) And subtype ('Home' 'Mint' '10.13' aso)
* lmms version