After submission you need to read your thesis to prepare for the viva.
Inevitably you’ll find a word that is in some way wrong. It’s not spelled correctly, it’s the wrong word, you meant something different or perhaps it is a string of words that don’t communicate what you need.
What do you do?
If the typo is simple then you have two choices: underline it in the text or make a clear list. After the viva, when you have to complete corrections, you have an easy-to-follow guide of what to do. You don’t need to correct them now. Marking it in your thesis or having a list is enough for the viva.
If the typo is more complicated then it’s probably best to make a note in the margin of what would be better for your thesis or – if needed – write a longer explanation on a Post-it Note and stick that in. Then you can explain things better – if needed – in the viva and complete the correction more easily afterwards.
Either way, a typo is just a slip that got past you when writing up. It’s part of the process. You get to make it better.