Hello @yann,
Welcome to Klaviyo!
Do you happen to be launching the Klaviyo app from the Shopify store? If so, instead of launching the Klaviyo app to access Klaviyo this way, I would suggest navigating to www.Klaviyo.com and logging in from the top right portal.
You’ll want to log in directly from the Klaviyo site, as the Klaviyo app found in the Shopify store is typically used just the first time to launch, connect, and integrate your designated Shopify store with Klaviyo. Repeated access of Klaviyo from the Shopify store has been known to cause customers to inadvertently create new Klaviyo accounts all integrated to the same Shopify account. This can cause further issues such as profiles/contacts being mis-attributed, signup forms not publishing/displaying correctly on your website, etc.
I’ve also mentioned this in a similar Community post which I’ve linked below:
Thanks for being a Klaviyo Community member!
David