In the amp menu there's a new knob called "GLOBL". If set to OFF the amp block works as normal. If set to GLOBAL1 through GLOBAL10, the amp will load the parameters from a "global amp parameter list".
As soon as you turn it from off it will load the parameters. If you then change a parameter, that parameter will be updated in the global amp parameter as well.
Any amps that use the same GLOBAL AMP will be affected. So, for example, if you set an amp to GLOBAL2 and adjust that amp to be a Plexi model with various drive, bass, etc., anytime you recall a preset with the GLOBL set to GLOBAL2 that amp will use the same parameters.