Funnel recommends default upload triggers based on the fields you select when you create or edit a conversion upload. You can change them if you need different behavior.
What upload triggers mean
Think of upload triggers as: If this field's value changes, should we send this row again as a new conversion?
Examples:
Returns — Including conversion value (or quantity) as a trigger can send a follow-up event when a purchase is refunded, so the platform can net out value (where the platform supports it).
Late-arriving attributes — If phone number is a trigger, a row that first uploaded with email only might upload again when the phone is populated. If phone is not a trigger, that change might not create a new upload.
Even when many triggers are selected, the destination may still count only one conversion per user or click if you configured the conversion action/rule that way (for example "Count one" in Google Ads).
Platform behavior differs: Facebook often cares most about user attributes staying fresh; Google Ads often cares about accurate sales and value.
Examples (conceptual)
Same user, multiple orders
If Conversion time and Email are triggers, a second order on another day typically produces another upload. If Order ID is also a trigger, two rows with the same conversion time and email but different order IDs can both upload.
Phone filled in later
If only Conversion time and Email are triggers, an update that only adds a phone number might not re-upload. Adding Phone number as a trigger can allow a second upload when the phone appears.
Returns
If Conversion value is a trigger, a row that changes from positive to negative value can upload again so the platform can record the reversal (Facebook may not support all return patterns—check current platform docs).