Sorry for the delay in response.
Could you please let us know the issue you are experiencing when trying to open bank documents? Is there any error message you are getting?
Are you trying to open pdf attachment from your email account?
Does this happen with a specific file or with all the files you are trying to open?
You may visit the following links discussing similar issue:
Also, let us know the version of Acrobat Reader and Android OS installed on the device.
You may refer to the steps given in this link for the same: Acrobat Reader Help for Android: Troubleshooting FAQs
Awaiting your response.