I believe the word you are looking for is "playhead" or "playhead cursor." I knew what you were talking about though. I assume that you are on a Windows machine. Here is what you will want to try:
1. Install all of your Windows updates.
2. Install the latest driver for your graphics card.
3. Uninstall any 3rd-party programs that might be affecting your graphics. That is unless it is from the manufacturer of your video card.
4. Open the control panel for your video card. It is usually located down in the bottom right-hand corner of the screen, next to your clock, in the startup tray. If you have an ATI card, it is usually called "Catalyst Control Center." See if you can find any settings related to antialiasing. If so, try turning them off. If they are already off, try turning them on. You may also want to check your settings for 3d rendering.
*If the control panel for your graphics card is not in the startup tray, check your programs in the Start menu.
5. Open Studio One and go to Studio One>Options>General and try disabling High DPI mode.
6. Try uninstalling your graphics card and use the default Windows graphics driver.