Translators using SDL Trados Studio may experience an odd behavior where new characters that are typed ‘eat’ the following characters. This is extremely annoying but the solution is quite simple!
If you are using Windows, you should be well familiar with the Ins button on the top of your keyboard (if you ever wondered what it was about, now you know it!).
INS means insert, i.e. new characters are inserted (added) before existing characters, while OVR means overwrite, i.e. new characters will overwrite any existing characters that follows.
If you are an Apple user and you are running VMWare or Parallels on MacOS to emulate/virtualize Windows, then you should clic Fn + Enter to switch between the Insert and Overwrite mode.
If you have a full Apple keyboard, then it is even simpler: just hit home (the arrow pointing in the upper left corner).
You can check which mode is selected by looking at the bottom bar in Studio.
Hope it helps!