How to stop preview of last used screen when checking which apps are open?

[AC Question]

I installed an applock to prevent people from accessing things like WhatsApp and to prevent uninstallation of apps.

Problem is, I have now realised that when I click on the bottom left option (on my Samsung Galaxy S6) to switch between open apps, it shows a preview of the last screen I used on WhatsApp. This could be a conversation meaning whoever uses my phone will see part of it.

Is there any way to make sure that there is not a preview when using the left tap button to switch between apps? Ideally I just want for the logo of the app to appear?

 

[Tim1954]

There may be a setting on the app lock application?
You can also make the device "forget" all activities as soon as you lock the screen.. You can find this on developer options > do not keep activities > toggle on.