Yes Niels, many years layer I just again started to test the program and not so used to yet.
Sorry for confusion. Situation happened while I am trying with the modifier keys and might be duplicated layer or something similar so at one point I saw dark pencil strokes with the lighter ones. Then I checked the opacity and saw that value and wanted to asked you because I first time saw maximum opacity value at 75. Quite surprised by the way.
Thank you for your help!