You're right - using the Value Field Settings does not always respect whatever formatting decision is in place (in the case of a metric), and the result can be a dollar sign in the report table.
Assuming Volume is a metric in your project, you could try bypassing the Value Field Settings in this case and instead construct your three table columns using Ribbon > Data > Insert > Insert Formula Column.
To generate your three columns above:
LM Volume V2 = TimePeriod(Volume,-1)
YTD Volume V2 = YearToDate(Volume)
QTD Volume V2 = QuarterToDate(Volume)
...the formatting of these three columns is controlled by the settings seen in the column creation dialog.
After typing the formula above, you can select a format of Number and 2 decimal points to match the format settings of the original metric.