This can be done in 3 ways.
Option 1 (Bulk Set all Listings with 1 Strategy)
The quickest and easiest way to assign a strategy is to bulk apply it to all listings from within the pricing strategy as below:
When in the strategy simply choose to 'Apply this strategy to all my active listings...' and click update.
Option 2 (Assign a Strategy to Multiple Listings)
Alternatively to apply different strategies to multiple listings. Click Assign a Strategy to Multiple Listings from the listings header menu.
Choose the strategy you would like to apply.
Select the products to apply this to using the tick boxes on the right hand side and then click Assign Strategy.
Option 3 (Individually Set Listings)
Click ' View Listings' from the header menu.
Locate the product you are looking for either by scrolling through the list or using the search box in the top right. Click the linkable text in the Strategy Column.
Choose a pre-set strategy from the drop down list. *You must also make sure a min and max price is set too if this was not done already. And finally click update.