Welcome to the forum stewartb132! First, For you all important links:
http://lmms.io/forum/viewtopic.php?f=1&t=4740
stewartb132 wrote:When I play a C on my Yamaha keyboard, LMMS interprets it as a C; but, the tone in piano roll is an Eb relative to the keyboard.
...that sounds really strange :/ -and there is not a 'tune to std' setting on your keyboard, you could have in a wrong position?
But lmms can fix this :)
You need to set the 'base-note'
on your lmms-instruments different from the std (as image)
When you move the green base-note, you can hear how the sound changes. You have figured out that your std setting A ~440 Hz correspond to YOUR Eb... I -think- that it means that if you place your base-note on Eb, you should have 440 Hz.. If it fits, could you confirm :)
You can read about all instrument-GUI-settings including base-note, here:
http://lmms.io/wiki/index.php?title=Instrument_Editor