How to use PA03/AREF as output ? [SOLVED]

72: error: request for member 'PMUXEN' in '1090536448u->Port::Group[0].PortGroup::PINCFG', which is of non-class type 'volatile PORT_PINCFG_Type [32]'

SerialUSB.print(PORT->Group[PORTA].PINCFG.PMUXEN);

Too complicated for my little head.
But does it disable only the PA03 functions? Or what else?
I do not see bit 3 in the code.

I also use PA31 and PA30 as input.
How do I disable SW debug?

#define In11 !( REG_PORT_IN0 & PORT_PA31 )  // SWDIO  - PA31
#define In12 !( REG_PORT_IN0 & PORT_PA30 )  // SWDCLK - PA30