“It is our duty to concentrate all our influence to make popular that which is sound and good, and unpopular that which is unsound (not good).”

Joseph Smith
I think what Joseph was trying to say by saying this is that every human being can tell right from wrong, and that what everyone should be doing is giving attention to what is sound and good. To what is positive and impacts us in a positive way. The negative and wrong things should have no attention and no popularity. I think he is trying to encourage us by doing what’s right so everyone can know the positive things that are going on. 

“It may make a difference to all eternity whether we do right or wrong today.”

James Freeman Clark

What this quote means to me is that the choices you make today are going to lead to the outcomes in the future. Every choice comes with a consequence and if you choose right today, you’ll get a good positive outcome but if you don’t you get a negative one. So everyday you have to choose the right to make a good difference in the future.