Glad to hear it finally started working out for you. Thats very exciting.
For each new resolution you use, you will have to setup the registration/convergence.
Hopefully the people who setup your projector did a good job with the fundamentals: physical placement, mechanical aim, lens flapping, electronic focus, and optical focus. Assuming that was all done well, what you need to do is setup the convergence.
The manual talks about setting it up without a signal, and usually that's whats recommended to set the thing up from scratch. You do the registration with no signal, save that to all inputs and then when you connect a signal it should be pretty close and you just need to touch it up.
In practice, it seems like many people (myself included for the first couple projectors I had) dont do that. Its frustrating to go throug the whole process with no input, get it nice and solid, then connect an input signal and see it go all out of whack. So I'd expect the people who setup your projector just did the convergence for the video signal you were using and the others are all pretty random.
You do have the remote control for the projector, right? It has buttons on the bottom row under a little plastic cover that you will need.
You'll have to go into the Service Mode with the secret code on the remote:
Enter Enter Up Down Enter
It will show you a prompt asking if you want to go into the Service Mode, say yes and then you can use the controls at the bottom of the remote.
Generally you setup the green first, then set red to match green, and finally set blue to match red.
You might want to go through each of the settings and make sure they are all set to 128 before you really start making adjustments. Its especially important to make sure the zone settings are all 128 since they will throw the other adjustments off if they have other values. Liberal use of the Memory button to save your current settings is a good idea once you've checked to make sure everything is set at neutral and then once you've started makign adjustments. I generally hit Memofy every time I switch from doing one adjustment to the next.
You will start with the Cent adjustment to center the green crosshair on your screen.
Then use the Size to get the edges of the test pattern to match yoru screen.
Hopefully green will be centered and the right size without having to use the Lin adjustment to change the linearity. If it does seem lopsided of off to one side, I'd recommend going back to the Cent adjustment and trying to get the center/size correct without using the Lin on green.
Then check the Skew to make sure the horizontal and vertical lines are plumb.
The Bow is used to get them to be straight up and down and side to side if there is any curve to them.
Then the Keystone is used to make the outer edges match the rectangle of the screen and be square in the corners. If I remember correctly, the D50 keystone has horizontal and vertical and when you adjust the green it affects the red/blue all at once.
After that the Pin is used to make the outer edges straight if there is any curve to them.
Hopefully, you can get the pattern nice and aligned with those adjustments. There are a number of Zone adjustments you can use to touch up individual areas of the image. The general recommendation is to try and get green setup as good as possible without using the zone stuff, and only use those adjustments on the red and blue if you really need to.
When I started trying to do convergence I would look at the whole screen and try to set the values and iterate until it looked good. But it often seemed like I would end up chasing my tail and going back and forth between various adjustments and never get it to be perfect. Then a more methodical method of using the digital values displayed and a little mental arithmetic to split the difference seemed to make sense and in practice has proven far more effective than trying to 'eyeball' the whole screen at once.
What I do now is focus on each adjustment on just one part of the screen at a time. Do each one just considering the horizontal or vertical components. First right and then left or top and bottom. Look at the number that gets one edge perfect, then do the opposite side and find that number. Split the difference and then do the other adjustment that compensates for it. After a few iterations I generally find that I end up at the right values that look right for both sides without pulling my hair out.
The adjustments work in pairs: Size and Linearity. Skew and Bow. Keystone and Pincushion. Each one in a pair will compensate for the other.
Starting with size and linearity, find the Size value that is perfect for the left side. Say its 110. Then do the right and find its perfect value, say 150. Split the difference and set it to 130. Then do the Linearity finding the value that is perfect for the left say 98 and then do the right say 122. Split the difference and set it to 110. Then go back and do the Size again - usually it will be much closer to correct for both sides and the difference between the ideal number on each side gets smaller and smaller. After a couple iterations its usually the same number. After doing the left/right do the top/bottom.
If the difference between two values is an odd number I usually bias it one way or the other, and often a single click iisn'tthat big a deal.
After doing the Size/Linearity, and Skew/Bow I usually go back and make sure the center is still good since sometimes those adjustments can knock it slightly off. Then after doing the Keystone/Pincushion on one rough pass go back and check the center, then Size/Lin, and then Skew/Bow before doing a couple more iterations on Keystone/Pin since they can throw the others off if they were way out.
Hopefully this description makes sense. The idea is to just look at each side of each adjustment in isolation, find the number that makes it perfect, then do the same on the other side. Split the difference between the two values and then do the same thing with the corresponding adjustment. Even if they start off way off, usually after a couple passes they converge (heh) on the same numbers.