In the past, most voters formed political opinions by listening to speeches, meeting with representatives of political parties, or attending town hall meetings. how do voters today tend to learn about political issues?

I believe the answer is: through human interest stories in the media

The media could adjust the way they provide information to appeal only to a certain group of people.
When these people learnt that a certain candidate is being praised for his/her character by the media, that chance that the candidate would be chosen would be increased dramatically.