If you do not want to leave your footprints on the profile of the person you viewed, you can set 'Do not leave footprints' with the following procedure.
For browser version:
Tap 'Profile' in the menu at the top of the screen
Tap 'Various settings'
Tap 'Footprint settings'
Select 'Do not leave' and tap 'Update'
For iOS and Android versions:
Tap 'Profile' in the menu at the top of the screen
Tap 'Various settings'
Tap 'Footprint settings'
Select 'Do not leave' and tap 'Update'.