Create Field Parameter Calculated by Column

Jonjon_99 

Specifically for your sample pibx, you could make changes to [%Total Units] as follows.

%Total Units = 
VAR CurrentMonth = MAX('Date'[MonthName])
RETURN
DIVIDE(SUM(SalesFact[Units]),
                        CALCULATE(SUM(SalesFact[Units]),FILTER(ALLSELECTED(SalesFact),RELATED('Date'[MonthName])=CurrentMonth)))

Or you can create another measure with this definition if you wish to retain the original measure for some other use.

In this case, change the line of 'Sales Type'[Sales Type] regarding %Total Units, to pointing the new mesaure you have created.

VAR CurrentMonth = MAX('Date'[MonthName])
VAR CurrentYear = MAX('Date'[Year])
RETURN 
IF(OR(ISINSCOPE('Date'[MonthName]),ISINSCOPE('Date'[Month])),
DIVIDE(SUM(SalesFact[Units]),
                        CALCULATE(SUM(SalesFact[Units]),FILTER(ALLSELECTED(SalesFact),RELATED('Date'[MonthName])=CurrentMonth))),
IF(ISINSCOPE('Date'[Year]),
DIVIDE(SUM(SalesFact[Units]),
                        CALCULATE(SUM(SalesFact[Units]),FILTER(ALLSELECTED(SalesFact),RELATED('Date'[Year])=CurrentYear))),
BLANK())
)

Jonjon_99 You have misplaced parenthesis. The below should be working.

%Total Units = 
VAR CurrentMonth = MAX('Date'[MonthName])
VAR CurrentYear = MAX('Date'[Year])
VAR CurrentQuarter = MAX('Date'[Quarter])

RETURN

IF(OR(ISINSCOPE('Date'[MonthName]),ISINSCOPE('Date'[Month])),DIVIDE(SUM(SalesFact[Units]),
CALCULATE(SUM(SalesFact[Units]),FILTER(ALLSELECTED(SalesFact),RELATED('Date'[MonthName])=CurrentMonth))),

IF(ISINSCOPE('Date'[Year]),
DIVIDE(SUM(SalesFact[Units]),
CALCULATE(SUM(SalesFact[Units]),FILTER(ALLSELECTED(SalesFact),RELATED('Date'[Year])=CurrentYear))),

IF(ISINSCOPE('Date'[Quarter]),
DIVIDE(SUM(SalesFact[Units]),
CALCULATE(SUM(SalesFact[Units]),FILTER(ALLSELECTED(SalesFact),RELATED('Date'[Quarter])=CurrentQuarter))),
BLANK())
))