Excel gives you several password boxes, and they are not equal. One of them scrambles your file with real encryption. The others just politely ask people not to edit. The method in the video, Save As then Tools then General Options then Password to open, is the real one. This guide walks that exact route and shows you how to use it without locking yourself out.
The video keeps it short: open the file, press F12, click Tools, open General Options, type a Password to open, confirm it, and save. Under a minute, done. What the short video cannot cover is why this particular password is the one worth trusting, what is sitting in the very same dialog that should not be trusted the same way, and the one habit that decides whether this lock protects your data or permanently deletes your access to it. That is what this page adds.
Password to open: •••••••• = REAL ENCRYPTION
Password to modify: (leave empty) = courtesy lock only
☐ Read-only recommended ☐ Always create backup
This is the exact method from the video. It works on an already-open workbook and writes the password into the file when you save.
One setting matters here: make sure you save as .xlsx. The modern format gets modern encryption. Saving back into the old .xls format keeps an old, much weaker style of protection alive, so let the file upgrade its format if Excel offers.
The Password to open is not a polite sign on the door. It changes what the file physically is. When you save, Excel encrypts the entire workbook, every sheet, every number and every formula, using AES encryption, with the password stretched through a deliberately slow chain of hash rounds so that trying passwords one by one is expensive.
Someone who gets this file without the password gets scrambled bytes. They cannot read a single cell, cannot peek at the values with another program, and cannot remove the password from the file, because there is no separate password stored somewhere to remove. The password is the key that rebuilds the data. No key, no data.
This is why the same dialog deserves respect in both directions. It is strong enough to protect a salary sheet or a price list that leaks by email. It is also strong enough that if you forget it, your own data is gone in exactly the same way. That honest trade is covered in the next sections.
Right under Password to open sits Password to modify, and it is a completely different animal. A file saved with only a modify password opens for anyone, shows everything, and simply opens read-only unless the password is typed. Any reader can read every value and can even save an editable copy under a different name.
That box has a genuine use: it stops a shared master file from being overwritten by accident. But it protects editing, not secrecy. If the video's goal is keeping sensitive data safe, the modify box alone does not do it. The same warning applies to the Review tab locks, Protect Sheet and Protect Workbook, which guard cells against edits but leave all data readable. One of the companion guides in this series compares those locks side by side; the short version is: for privacy, only the open password counts.
Encryption this strong makes the password itself the weakest link, because guessing is the only way in. Help yourself properly:
Thirty seconds of testing saves the classic disaster story. After saving, close the file fully and reopen it. First type a wrong password: Excel must refuse. Then type the right one: the file must open normally. Only after both tests pass should you delete or overwrite anything else.
Until you have done this once or twice, keep one unprotected copy of the file somewhere private as your safety net, for example in a folder only you can open. Once the routine is familiar, delete that copy, because an unprotected twin quietly defeats the entire point of the lock.
The video sets this password on a real Excel file in about a minute, including the confirmation step and the save.
Watch Full VideoYes, they are two doors to the same lock. File, Info, Protect Workbook, Encrypt with Password sets the same file-open password that the video sets through F12, Tools, General Options. Whichever route you use, the result is the same AES-encrypted file that asks for the password before opening.
You set the Password to modify, the second box in General Options. That lock never encrypted anything: the file opens for reading, and the password is only requested when someone tries to edit and save over the original. Clear that box, put your password in the Password to open box instead, and save again.
No. Your sheets, values and formulas stay exactly as they are. Excel encrypts the saved file on disk and decrypts it in memory when you open it with the correct password. The only visible difference is the password prompt at open, and the file cannot be read by any program until that prompt is passed.