if you want the angelfish to live you will need to heat the water to 80F. Get a thermometer, not one of those stick on strips...
80 will kill goldfish.
If you try to mess with your PH it will only cause the levels to go up and down all the time and will stress your fish and kill them.
You might try the salt when you first put in the fish. Make sure you dissolve it well. It can help to prevent ick outbreak if the fish you buy have it. Or other bacteria. The fish you get can be sick without showing symptoms until they are stressed-like being moved. After a couple weeks, the salt should start to be slowy moved out with water changes, just don't add it back in. Once your tank is established you can start a quarantine tank for adding new ones. If you add a new one later and it is sick, expect it to cause outbreak in all of your previous fish...costing you lots of money.
The yellow color in your tank is most likely your light. Find out what it is, and try something else. If you still have the box, you may be able to trade it for a different one.
In my experince UGF are not too good. HOB is better. or canisters.
Angel fish like still water and are very shy at first. They stress easily and do not like other tankmates that are 'busy' or swim actively. They are also slower eaters, so more fiesty fishies will chow the vittles down leaving them nothing. Their long fins are perfect 'game' to other fish, who pick them to death if they are not with compatible tankmates. Semi compatible will not do for angels. Especially in a 46 gal.
By the way GoldFISH are fish.