PhD graduates have rarely told me they’ve forgotten an important detail in the viva. Usually everything comes to mind when needed.
But nevermind others: if you’re worried that something important will slip your mind you can do things to help yourself. Just for starters:
- Make notes, don’t just read and re-read your thesis.
- Bookmark details, make it clear where you can find them.
- Highlight important passages on pages.
Your examiners don’t expect you to commit three or more years of work to memory. The worry comes from you. The solution can too.