Yes, your firmware is v1.54. v1.55 is the latest available for the 568 - its on the M software download section. It may not be worth updating - if its not broke etc. The 568.2(mm) has had more recent changes, some of which, v2.5, are very significant changes.

I think you need to use a PC to set up speakers as being large. IIRC, they are effectively all treated as small otherwise and the sub XOVER setting will do the redirect of bass to the sub. Revisiting the manual, it looks like its an all or nothing setting and can't be done on a speaker by speaker basis. I run small all round so this was never a problem for me.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).