Can app access the text in my default memo app? I use Samsung Galaxy S2 and store some personal data in the default memo. I have updated the phone to the latest version. Can any app just access the data in my memo?
Nope. No other 3rd party app will be able to access your data in the memo. Applications on your phone are sandboxed meaning they can't access other apps data.

Check this:

&gt; The Android Application Sandbox, which isolates your app data and code
&gt; execution from other apps.