Hello @Susie,
Great question!
Changes made to a flow are not retroactive to those customers already going through the flow. I would recommend taking a look at the How Contacts Move Through a Flow article to learn more about making changes to a flow can effect and impact your customers.
One work around to updating the time delay for these contacts who are still caught in the original time delay timeframe would be cloning this flow, making any changes and updates you want to the new flow, setting it Live, and then back-populating the flow. Once you are sure these contacts are being filtered and going through the flow as you expected, you can turn the old flow off. Using this method of cloning, updating, and back-populating will work as Klaviyo is essentially re-qualifying these existing contacts for a new flow with the desired updated settings.
You can learn more about Klaviyo’s back-populate function and how to initiate this process from both the How Back-Populating Works in Klaviyo and How to Back-Populate a Flow articles. I would also take a look at a recent comment I made in a Community post on the same subject of back-populating which i’ve included below:
I hope this helps!
David