So on questions such as how sunsets occur on flat earth etc there is not a universal response from the FE crew...Pete Svarrior confirms that Tom Bishop does not represent their views, Junker chucks threads to nonsense and J-man talks 'God did it' and other bollox, so I ask where is (and why not) is there a community answer to basic RE problems with the FE theory? You have no agreed map, answer to sunsets, moon appearance across the earth, pinhole camera observations etc so if you three can't even agree how do you hope to persuade us?
Under the Globe Earth model, the sun doesn't rise nor set. Being as we rotate around the sun the sun would appear to rise and set depending on how far away it is from us. AKA Perception. That same law of perception would also apply to the flat earth model being we perceive things to look the way they due because of how our brain and eyes work. My point is in a flat Earth, the sun rotates around us, meaning the further the sun is from us it would appear smaller and smaller causing it to appear to set. However, it hasn't!
You have half of that correct - it would appear smaller and smaller as it receded into the distance. This is not what is observed in reality. The size of the sun stays pretty constant due to its size and distance.
Have you ever been on a beach, something we have a lot of here in Panama city, Panama , but really seen how the sun looks overhead and how it looks right when it meets the horizon? They are nowhere near the same size and depending on how close you are to it, based on how it rotates (your Earth, or my Sun) it would appear larger or smaller at the Horizon due to the season. The tropic of Cancer and Capricorn dictates the seasons. No matter which model you use. 
The sun itself is almost exactly the same size regardless of where it's being see. The light/corona around the sun is what's magnified some by it's setting. Look at it with a proper filter (welding mask rated over 16 or so, or one of those eclipse glasses) and you'll see the actual orb of the sun doesn't change in size. Well it'll change very slightly, but nowhere near the amount the FE distance change would dictate.
Would you please point us in the direction of what it is you are talking about? Once again, what you have described is the opposite of what we see day in and day out as we look at the sun. What happens when you focus on a dot? Does it mean that everything else around it has disappeared? Well, perceptive will tell you that it has, but the reality is it hasn't! Flat Earthers believe that the moon and the sun are about the same size. but depending where you are on Earth and the time it is, the Sun will look bigger/smaller than "normal" and noticeably because of preceptive.
First, you can't see the disc of the sun overheard. It is FAR too bright. As has been mentioned, you need something to filter out the glare. When you do this and observe the sun, it stays almost the exact same size all day. That is because it is very large and very far away. FE theory can't possibly be right because they small sun only a few thousand miles away would substantially smaller as it moved out of sight.
The problem is IDENTICAL to the problem with the moon...but with the advantage that staring at (and measuring) the moon doesn't trash your vision!
In RET terms, the moon is a lot closer than the sun - but it's still far enough away to show very little parallax or other weirdnesses.
In FET terms, the sun and moon are claimed to be about the same size and at about the same distance.
So whatever problem you might have with the sun - you should also have with the moon...and similar explanations should apply to both.
So both sun and moon are within a few percent of being the exact same size all day, every day, all year and for at least the past million or so years. They are the same when vertically overhead as on the horizon.
You can demonstrate this for the sun - either with a #12 welding glass (which cost a couple of bucks on Amazon) - or with one of the couple of million pairs of eclipse glasses that were recently sold and will be collecting dust for quite a while!
Or - you can do it with the moon...which is essentially the same deal.
When the moon is at zenith, it's the exact same size it is when it's on the horizon. The easiest way to convince yourself of this is to go out when there is a full moon - hold a penny at arm's length and line it up next to the moon. You'll soon be convinced that the size doesn't change at all.
This is a BIG problem for Flat-Earthism. The claims are:
1) Magic perspective squashes it to the horizon (but how come it doesn't squash the moon into a flattened oval too?)...and...
2) Big, bright glowy things defy the laws of perspective by remaining the same size, no matter how far away they are. Tom likes to show photos of rows of streetlamps that kinda show this effect - but then stops answering the thread when people point out the explanation for that and the many reasons that this cannot possibly be true.
Neither of these solves the problem...not by a long shot.