You should always append Sub ID and Shared ID parameters on impact.com. They should be added before you copy the code from the platform.
The method below can be used to fill static values that do not change as well as dynamically populated values for the tracking link's Sub IDs and Shared ID.
From the top navigation bar, select Content → Assets.
Select the asset to which you want to append these parameters.
On the right, select Tracking Link.
Toggle on Tracking Parameters.
Use the fields to add Sub ID and Shared ID values.
Under the values, select Save. A fresh tracking code will generate that you can use.
Alternatively, the method below uses the Dashboard Create a Link widget to quickly fill static values for the tracking link's Sub IDs and Shared ID.
From the top navigation bar, select Home.
Find the Create a Link widget on the dashboard, then select Advanced.
Use the fields to add Sub ID values and a Shared ID value.
Note
Links created using the Create a Link widget cannot use dynamic values (e.g., {token}). These can only be created by following the first instruction set above. See the FAQs for the character limits for Sub ID and Shared ID values