Hi Nowler,
I don't trade Forex and I don't use volume - so take anything I say on the subject with a bucket load of salt! Perhaps someone who does understand and use volume will add a comment.
The number of times that prices change is not the same as volume. Volume records the number of contracts / shares etc. that are traded. But even this definition can vary according to the market traded. For example, the NYSE and Nasdaq measure volume differently. For every buyer, there is a seller: 100 shares bought = 100 shares sold. The NYSE would count this as one trade and as 100 shares of volume. However, the Nasdaq would count each side of the trade and as 200 shares volume.
IMO, the number of times a price changes is unlikely to be of much help to you as price can move up or down just one point but the recorded volume could be in the many thousands. On top of that, there are various ways that volume can be displayed - assuming you're using charts rather than reading a Level 2 screen. Vertical bars beneath price on a time based chart is the most common. But there are others such as:
Candle Volume,
Equi Volume and
Volume by Price. And then there's indicators such as
VWAP - very fashionable among equities traders a few years ago.
IMO, volume is something of a minefield and using it to enhance your edge is an advanced technique best left to experienced traders with detailed knowledge and understanding of their market. Clearly, for these traders, volume can be very useful. For traders who are not in this category, volume is more likely to muddy the waters than it is to add clarity. This is especially true for Forex as it's not an exchange based market. Therefore, knowing exactly what Oanda (or whoever) are showing you with regard to volume and making use of it is likely to be very challenging. Having said that, don't let me put you off!
Tim.
PS. I forgot to say that if you want to pursue volume further then the resident forum expert on the topic is
dbphoenix. Here's an old thread of his which is more about price than volume - but it'll give you an idea of how he approaches it:
Price, (Volume), Support, Resistance, Demand, Supply . . . (Abridged)