OfficeSuite lets you protect your document on a file level, allowing no one to view the file, unless they have the password.
Password-protect a document
1. In View mode, tap the menu in the top right. Tap Protect, or In Edit mode, on the File tab, swipe the toolbar to reveal more options, tap Protect.
2. Type and retype the password.
3. Tap OK.
4. Save or Save as the document.