Hello WolfyMay, apologies for the late response.
Don't worry, it's not a silly question and it's good that you asked because you never know if someone else might be having the same issue as you and are looking for the answer. So this info can benefit them as well C: To be honest, I've never encountered a problem like that and I'm not quite sure how to fix it. But, I can try. Quick question, when you first tried this tool, what was the size of your canvas (Width and Length and what resolution was it at? When you create a new Sai document, what are your settings? Canvas size and resolution)
Don't worry, it's not a silly question and it's good that you asked because you never know if someone else might be having the same issue as you and are looking for the answer. So this info can benefit them as well C: To be honest, I've never encountered a problem like that and I'm not quite sure how to fix it. But, I can try. Quick question, when you first tried this tool, what was the size of your canvas (Width and Length and what resolution was it at? When you create a new Sai document, what are your settings? Canvas size and resolution)
That's ok, I'm just glad you replied! 
and I Actually just use a drawing of mine and take a picture using my smart phone and send it to my laptop then open it up in sai 
then outline it. The thing that bugs me is the last time I used sai I had no problem with the lines and it turned out decent. So the only thing I can think of is when I was messing around with the settings, I was able to change the way the lines looked. And now I completely forget what I did to make it look like that...
and I Actually just use a drawing of mine and take a picture using my smart phone and send it to my laptop then open it up in sai then outline it. The thing that bugs me is the last time I used sai I had no problem with the lines and it turned out decent. So the only thing I can think of is when I was messing around with the settings, I was able to change the way the lines looked. And now I completely forget what I did to make it look like that...