Printing issue on top layers

[ikeke]

Hello,

I just join the S3D user family and encounter a problem i didn't have when using Cura 15 provided with my Alfawise U30.
When i print something and the top layer are not flat, i have an awfull result as you can see below:

print.jpg (16.25 KiB) Viewed 485 times

When i print a box with a cover for example, everything is clean. It's only where there are round shapes.

Could you give me some advices on how to fix that ?
Note: i use an Alfawise U30 FFF profile provided by the support team.

Thank you,
Matt
(Sorry if i made mistakes but english is not my primary language.)