Many themes have the option to display the compared-at-price (with a strikethrough) of a product whenever it is larger than the price. Some themes can also display the size of the discount, either in percentage or in dollars. There are three possible reasons why this feature is not displaying on a given product.
Reason #1 - Your Compared-at-Price is not high enough to trigger this feature
To test this, select a specific product and ensure that it's compared-at-price is higher than it's price. Then open the product page and refresh your browser to see if the desired feature appears. If it does, you can bulk edit the rest of your compared-at-prices using our Bulk Product Edit app.
Reason #2 - This feature is not enabled in your theme's options/configuration
If the compared-at-price is still not showing despite being higher than price, this indicates that your theme is the problem. This does not necessarily mean that this feature is not available. Plenty of themes have this option even if it not enabled by default, so hopefully yours is one of them.
To check, please take a look at your theme options by going to Online Store -> Themes -> Customize. You should be able to see the relevant theme settings by opening a product page while in Customize.
Example Screenshot: The following example is taken from the settings of Supply theme. If you are using a different theme, you will likely see different options. This image is only intended as an example of where to look.
Reason #3 - Your theme does not have this feature
If your theme does not have this feature, it is possible to add it by customizing your theme. However, this option would require you to hire a developer and could be expensive and time-consuming.
Either way, our recommendation in this case is to contact the developer of your theme. They are in the best position to assist you, as they are already very familiar with this theme. They can either update the theme to add this feature, or request access to your shop to implement it for you as a customization.