So, my question is, when you want to target different countries and sell the same product should you only change the location in the ad set to the countries that you want to sell and target only English speaking people, or should you change the whole interests and the language of the ad set because I suppose the interest won't be the same for different countries?
In my case, I want to sell my product only to English speaking people but in different countries.
Great question and in short, I think it really depends on your niche. While certain countries will have their own unique nuances in terms of their societal structure which would be important to identify in some industries that you are selling in. For example, I think fashion and apparel would be applicable in this sense where interests could vary between countries.
On the other hand, there are also industries that I think would have very similar interest groups, regardless of country. For example, if you are selling camping/hiking equipment. These interests are going to be transferrable across countries because your ideal customer is someone who enjoys the outdoors, camping, backpacking, hiking, etc.
My general rule of thumb is if your products pertain to a specific lifestyle, targetting interests on your ad sets across multiple countries are going to be more or less identical. Whereas other industries that do not may have their own unique interests based on the country.
If there is anything else I can help you with, please let me know.