question: in case there is an error in the data concerning the subscriber, he or she has the right to have the error corrected.
Capitalize this past sentence correctly.
A: In case there is an error in the data concerning the subscriber, he or she has the right to have the error corrected.

question: in the case that your dm file doesn't open, it is highly likely that you do not have the correct software application installed on your pc to view or edit dm file extensions.
Capitalize this past sentence correctly.
A: In the case that your DM file doesn't open, it is highly likely that you do not have the correct software application installed on your PC to view or edit DM file extensions.

question: if your pc opens the exs file, but it's the wrong application, you'll need to change your windows registry file association settings. in other words, windows is associating exs file extensions with the wrong software program.
Capitalize this past sentence correctly.
A: If your PC opens the EXS file, but it's the wrong application, you'll need to change your Windows registry file association settings. In other words, Windows is associating EXS file extensions with the wrong software program.