These are detailed in the User Guides, available to download on the relevant product page.

Options are of 2 types:
Jumper Options - move jumpers to desired position
Solder Options - requires use of soldering iron and sharp knife.  *****

*****  If you have any doubts about these procedures, please contact your dealer
or local  Allen & Heath and we will put you in touch with your nearest service centre.

 

Jumper Options:

Mono Input Channels
Aux pre/post insert/EQ : pre / post
Direct Output Source   : pre / post

Stereo Channel
Aux : pre / switched / post
Aux : mono/stereo 

Aux Master
ST1(5) : mono/stereo

LR Master
LR mix to AB : pre/post

Solder Options:

Mono Input Channels
Aux : pre/switched/post fade

Aux Master
electronically balanced option    
additional parts required, more information <here>