Unable to create monospace font-headers with fontcreator

Dear community

I'm trying to create a monospace font file for use with a GLCD using fontcreator2. Unfortunately, as stated by others in old forum posts, the program makes variable width fonts from every font that is imported - even when monospace fonts like Courier, Lucida Console etc. are used. Does anyone have a tip, solution or workaround for this problem?

Thank you very much,

Dani in toscany