Obsessions will tend to persist if avoidance and/or compulsions are
involved. I advise you to get involved in some cognitive behavioral
therapy.

Doing some exposures where you line up I letters will help you. Maybe start with a just a few i letters. It may sound paradoxical but the pathway out of anxiety is exposing yourself to whatever you fear(take baby steps, the exposures should invoke moderate anxiety not overwhelming anxiety) and over time the fear will lessen.

Again, this is best done under the tutelage of a professional CBT therapist.

It probably will eventually. Almost all of mine come and go. But they are always replaced by something else. The idea is to learn to deal with the OCD itself instead of the individual obsessions. CBT and ERT work for the symptoms, but not always for the disease. I'm not saying you shouldn't practice these things. The better you get at recognizing the symptoms as foreign to you, the better off you'll be. But eventually, you have to learn to quickly identify the thought and dismiss it before you need exposure, etc. It can be done, but until a cure is found, you'll probably always have to practice this.

One comment Clutter: once you gain confidence applying ERT to one obsession you can apply it to another. Also, you learn not to practice avoidance and/or compulsions. That being said, cognitive techniques are also important. I look at it as having a toolbox, the more tools the better.