[Elecraft] k3 filter setup /question

[john]

I have a k3 with the standard 2.7 filter and a 400hz cw filter 
installed.  The 2.7 is in slot FL3 and 400hz is in slot FL4.  My 
question is when you are adjusting the width of the filter should the 
filter 3 number change when FL4 filter engages?  When I adjust my width 
down from 2.80 down to0.05 it always shows FL3 on the display.  I have 
watched some Youtube videos and notice that the FL# changes.  That may 
be because they have more than 1 cw filter.  I know that you must 
transmit through the 2.7 filter and that is the way that I have it setup 
in the K3 utility program.  Everything may be working like it is suppose 
to but was just curious about why my radio does not show FL4 engaged 
when adjusting the width control.  Also when I manually hit the FL4 I do 
not hear any signals.  It seems to wipe them out.
Thank-you
John KM5PS