What do you mean by 'fast change capability'? In QlikView context, the only Fast Change I know applies to the ability to quickly switch between different chart types. This does not change the dimension of the chart, only the type.
If you're looking for a way to change dimensions without going into the chart properties, it can be done with a variable.
=If(vDimChoice = 1, DIM_1_FIELD, DIM_2_FIELD)
Then by changing the variable value, you can change the dimension. The variable could be changed via a slider or input box.
