When I plug my headphones in (I have apple headphones) the icon shows up for a second then disappears. How do I fix this?
It's very likely there's something wrong with the 3.5mm jack. My brother had the same problem, he'd have to replace the jack but it was better to just replace the phone since it was an older one.
Test the headphones with some other music device, like an MP3 or radio and see if the same problem persists. This way you can be sure there's nothing wrong with your headphones.
If the headphones just wont work with the LG I would assume that it is the smartphone. Would be interesting to know if there are similar issues with other headphones, too. But anyway, lets start.
I had a similar issue, too. You could try to look for hardware issues. Maybe there is just something like cotton in the headphone jack. To try this just take a torch and look into the thing, if there is something inside try to get it out of there with some wooden or plastic toothpick for example.
If there is no hardware issue you should look for system updates (which you should do anyway) first, maybe the issue will get fixed with some new software. You could also try to reset your smartphone or get a custom rom.
If it is not the headphones and nothing in the hardware you can see or some software issue there could be some comatibilty issues with the voltages of your headphone jack and/or the inner resistance of the headphones. If this is the case there is nothing really I could imagine you might want to do. Maybe you could try to tweak android to make what you want it to make, but I dont have this smartphone and cannot tell whether this will work or not.
Hope I helped you.