Dear Programmers

Please I humbly and seriously still
seek your help with regards to my phone.
I use Tecno W2 with Android 6.0

I realised that a Trojan had entered my phone, and when Avast failed to resolve the issue, I had to format the phone.
After formatting, I went to Google Play Store to download and restore my apps.

Suddenly I started getting a message as follows:
YOU HAVE TO TURN OFF SCREEN OVERLAY in settings.

I delved in and tried to fix it by removing permissions for various apps. I eventually removed overlay permission for everything to no avail.

Then I went online to read. I realised that it's usually a certain type of App that causes it. I tried to find the culprit all in vain.

I also learnt that overlay comes usually when one app seeking permission is open and another seeks permission.

I formatted the phone a second time and being very careful to ensure one app does not remain open while the other seeks permission.

I succeeded for a while but as I'm writing this, the story has changed again. Screen overlay permission.

I can't even upload the screenshot of the issue.

Please help me. I need to get this done.

Thanks a lot in anticipation.