Hum. I hope this does not sound rude.
Do you really think that the camera makes the photos to be dull?
I tried every way from changing the settings
Do you know what the settings are for? Well, does not matter at this point. For now just stick with the "A" option (Aperture priority)
Trying all the rooms in my house
This potentially work. But why don't you post some examples of each room and help us help you see the diferences?
to buying a new photography light box.
Again, this potentially work... Where is the example of that light setup... What is that light setup about? Some external flashes? A light tent? The only image you linked is using the built in flash, which almost never work.
I need my pictures to look professional and catchy.
Hum. For a photo to be porefessional needs to be so.
The good news is that you do have the notion that lighting is the most basic flaw of your photo.
Turn off the built in flash. Every other option will look better than that.
Put the cake next to a window, with natural daylight light. Direct sunlight? Not in direct sunlight? That needs to be experimented. Probably start with indirect sunlight.
Make a simple google search of cake photography https://www.google.com/search?q=cake+photography and see the results.
Move yourself, put the cake next to a window and let that window show, use a wood table use the white backdrop you have, move down, move closer, move further away...
Making adjustments later
You can always adjust contrast and saturation later. Normally this two things makes a photo more "catchy", but the previous steps makes a photo more "pro".
pictures to look professional
Wellcome to the world of photography. This goal could be achived practicing and seeing, seeing and practicing.
Make some changes on what are you currently doing. Any change will improve. Also will have new problems with it, but you can then ask for more specific issues and improve further.