EC2 instance Launching and Changing Configuration

Hi, We are new startup. We need an EC2 instance as g5.4xlarge instance type with 512GB SSD. Because of the limitations of vCPU I couldn't launch instance . I decided to create the instance within the limitations. There was also a warning about storage limit on the EC2 configuration page. So I had to configurate the SSD capacity as 30 GB. I created instance as t2.micro instance type. By the way I had created a request to increase the limit of All G and VT Spot Instance. I recieved an e-mail about it. Our limit was determined as 8. When I tried to change instance type g5.4xlarge, I got the error : "You have requested more vCPU capacity than your current vCPU limit of 0 allows for the instance bucket that the specified instance type belongs to." . So I tried to change instance type g5.2xlarge and succeded. Now I want to request increasing limit of vCPU but When I try it I get error "Only one open service quota increase request is allowed per quota." And I also want to increase my storage capacity but I can't find any setting in actions of launched instance. Could you please help me to change our instances configuration as we need. Thank you