How to effectively eliminate stringing in 3D print
Note: The image in the question was changed after the question was asked. This answer is out-of-date with respect to how the question has changed; I'll update it when more information is available.



These don't look like strings, which I'd define as material deposited outside of the model, but rather damage done by moving the hotend through already-printed material without retracting. In Cura, this is called "retraction combing", and it defaults to "all", which is way too aggressive and visibly harms the surface finish. Switching it to "noskin" or even "infill" only will make this go away and greatly improve your print quality, at the cost of some speed. The cost can be severe in worst case with certain kinds of fine detail, but usually "noskin" is cheap and suffices.