Indicating inversion for chords.

I am placing chord names above the measure and indicating them by "b", "c", etc. for which inversion is used. When I put a "b" against the chord name e.g. Amb or Am(b) the system changes this to a B flat symbol. How do I prevent this? Or maybe an alternative way. This is not a proper music piece but a progression score for own use. Looked in manual under "inversion" but no luck. Thanks.