What pairs are generally affected by the news?

Sounds like a broad question and i have tried to read up about it but for instance, earlier i spotted a news event for canada, i thought i would try and trade it on demo using USD/CAD however it made no impact on the market yet it was a strong piece of news. I switched over to USD/JPY and the market had risen alot since the news so would i have been better trading on that currency instead? if so how do you tell which is the best currecy for news events? Even though i am new to news trading i have however been reading up on it for the last 3 weeks but still unable to figure out this.

There’s a lot of complexity in trading on news. You need to know how important a given item is to the market, and what the market has “priced in” in terms of the outcome. Of course you need to know the primary currency the news is likely to influence. Just as importantly, though, you need to know whether the currency on the other side of the pair(s) you’re looking at is the more dominant influence at the time. It takes a lot of time watching this stuff, and even then there are no guarantees.

Always look at the releases which normally has a high impact on the price action.Trade only the very important news events and never forget to take a look at the previous month’s price action at that release.You may check the history of spike charts here:
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