Uppababy Vista sun canopy problem?

[Landl]

I have a Vista 2015. Now my daughter has grown I have tried to adjust the sun canopy on the toddler seat upwards to give her more headroom. However as soon as the buggy is moving the canopy just slips down to the lowest position again.
Does anyone else have this problem?
I’ve looked at the instructional videos and there doesn’t seem to be anything on the hood to click the canopy into to hold in place. Unless I am doing something totally wrong?!
Any thoughts please?
Thanks
From the mother of a toddler who can’t see out of her buggy unless it’s cloudy