boardcomputer time setting

tach people, I have a problem again: I have just installed a board computer and now have no idea how to set the time. of course the switch is also installed. and then I read here in the forum that the computer has to be reprogrammed somehow if you have a different engine in it. alo the computer comes from nem 16V but I only have an 8V. can you do it yourself or how does it work? gruss christoph