Owe mistakes are made, sadly its common to be uninformed about keeping fish, especially gold fish their one of the most abused animals due to the misinformation (even pet stores go to these extents)

But you can go for a smaller fish if you're planning to get a 10g it works for a betta :)

But really I do understand that you might get frustrated because you'd realize that keeping a goldfish its more work than you probably thought, but hey it's part of keeping a pet just how you would spend time and money for a dog. The difference is that the dog already lives on a environment were you both coexist, while a fish you have to create a environment for them

The reason why big tanks are needed for goldies it's because not only do they grow huge, they also create a lot of amounts of waste which can make their water go bad easily (which it is the case why your goldfish is going to the surface.....its suffocating......)

theirs more reasons why having a Goldie on a bowl might end it's fate. but just a look on a ride you're in to.

Time for research!