Hello Charline87,
It sounds like you were having some difficulty navigating your continuity features to ensure your devices aren't able to access the same browsing information. We recommend ensuring that Handoff is disabled.
"Go to Settings > General > AirPlay & Handoff," then turn off Handoff.
For more information on using Handoff please refer to: Use Handoff to continue a task on your other devices
To ensure your devices continuity features can perform to their optimal capabilities, we would also recommend making sure to keep your devices updated.
We appreciate you reaching out to Apple Support Communities.
Cheers!