App Lock
Ask for a fingerprint or your phone PIN before the book opens — so an unlocked phone in someone else's hand still shows nothing.
Your book is already encrypted on the device. That protects the file — someone who copies it off your phone gets nothing readable.
App Lock protects the screen. Without it, anyone holding your unlocked phone can tap the Businessly icon and read every balance.
Why this matters even more now
Businessly can now sign you back into your account by itself when you set up a new phone — see Signing in on a new phone. That gets your book back faster, but it also means a phone that ends up in someone else's hands can carry your sign-in without them typing anything either.
If App Lock was already on, Businessly carries that choice across too and switches it back on for you on the new phone — checked against whatever screen lock that phone has, exactly as App Lock always works. If the new phone has no screen lock at all, Businessly will not switch App Lock on with nothing behind it: it stops on a one-time screen asking you to set a phone lock first, before it finishes signing you back in.
App Lock is what stands in the way. It is a separate secret — your fingerprint, your face, or your phone's own PIN — checked fresh on whichever phone you are holding, not something read out of a backup or your Google account. Whoever ends up with the phone still has to get past App Lock, even after a sign-in has already come back on its own.
Turning it on
Go to Settings and open the App group — or type lock in the search box. Switch on App Lock.
From then on, Businessly asks for your fingerprint, your face, or your phone's PIN before it shows anything.
If it is off, Businessly will ask
Once you are signed in, a card turns up on Home now and then if App Lock is still off, suggesting you turn it on. It is not a one-time ask — it comes back a few times, spaced further and further apart, then only occasionally after that.
This nudge only shows once you are signed in — a guest is never asked. App Lock works exactly the same either way; signing in just means the card is there to remind you.
Your phone needs a screen lock first
App Lock borrows your phone's own lock, so your phone has to have one. If your phone has no PIN, pattern, or fingerprint set, Businessly will tell you and offer to open your phone's settings so you can add one.
Fingerprint or PIN — it remembers
If your phone has a fingerprint (or face unlock), the lock screen offers that first, because it is the quickest way in.
Underneath it there is always a way to switch: Use PIN instead. Tap it if your finger is wet, or the sensor will not read, or you simply prefer typing.
On a phone with no fingerprint, there is nothing to choose: it simply asks for your phone PIN.
If your phone is an older one
Some older phones — before Android 11 — will not tell an app whether its fingerprint sensor may be used, even when that sensor works perfectly well. On those phones Businessly used to offer the PIN only, and went straight to your phone's own PIN page.
Now it stops on the Businessly screen and offers Use fingerprint instead anyway. Tap it once. If it works, Businessly remembers and leads with your fingerprint from then on.
If your phone turns out not to accept it, Use PIN instead is right there on the same screen, so you cannot get stuck. And Settings › App, under App Lock, carries a Fingerprint check — details line on these phones, which you can tap to copy what your phone reported — handy if you ever want to tell us about it.
Choosing when it locks again
Under Lock after you decide how long Businessly may sit in the background before it asks again:
| Choice | Good for |
|---|---|
| Straight away | The strictest. Locks the moment you leave the app. |
| 1 minute | The default. Answer a call or check a message without re-authenticating. |
| 5 minutes | Hopping between apps at the counter all day. |
The hidden benefit: no preview, no screenshots
While App Lock is on, two more things change:
- Your book cannot be screenshotted.
- Your book does not appear in the recent-apps preview — the small live picture Android shows when you swipe through open apps.
That second one matters more than it sounds. Without it, someone flicking through recent apps can read your balances without ever opening Businessly, so no lock screen would ever have been shown.
On Windows, App Lock asks when you start Businessly, using Windows Hello or your Windows password. Windows has no equivalent of the screenshot and preview blocking above.
What App Lock does not do
Being straight about the limits:
- It does not protect against someone who has full technical control of the phone — a modified or "rooted" device. It is a door, not a vault.
- It does not encrypt the files you export yourself. A spreadsheet you export is a normal file on your phone.
- It does not replace a backup. See Backup & restore.
For where your data lives and what leaves the device, see Your data & privacy.