How I need to do to open pdf files in Adobe pdf reader as main program?

Hi @Claudio229494083atd,

Whenever you try to open a file that Acrobat Reader supports, your android OS will ask you to choose the application to open and provide you with two options, ‘Always’ and ‘Just once.’ Select ‘Always’ to make Acrobat Reader a default application for that file type.

However, if you open a different file type, it will give you the same option again. To learn more about opening a file in Acrobat Reader, please refer to Open a file. 

Let us know if you have any questions or need any help.

Thanks,

Bhupesh