The front and rear derailleurs have nothing to do with each other. Rears wear out a lot faster because they have running parts; only the spring can wear out on a Front. My previous Front lasted 17 years; Rears last me about 5.

Shimano used to provide instructions for how to adjust derailleurs in the box; now they're on their website. It's pretty simple.

Also check the angle of the derailleur: if it's rotated to far one way or the other it won't work properly.

You may have another problem: worn teeth on chainring(s), worn chain, loose shift lever. A chain can come off a chainring even with a properly-adjusted front derailleur if it shifts quickly from the largest to the smallest of a triple, as it would if the lever keeps on moving after you take your hand off of it.