Need Help Changing to an Adult Account

So I've been trying to figure out how my "child" account can change to an adult account for xbox one. I'm 18 years old and the birthday listed on my account is correct. I keep reading that the account is supposed to change automatically, but mine hasn't?
I keep seeing this link suggested to other people with a similar problem: Xbox One : Family I went there but couldn't find anything that was helpful.
Any suggestions? Will removing myself from my family account help?

:)

 

Xbox Adult account accidently deleted

Hi I have just got an Xbox one for X mas and I made account and it was all working
I then bought gold and I was fine until I tried to buy a £35 giftcard (today) to buy the BO3 Season pass and I got the 35 on the console to buy it and when I tried to buy it of the store it said I wasn't allowed and I needed to change settings in online privacy and allow buying online
turns out my brother had deleted the adult account and I can't get back on it as It is deleted I have tried creating new adult accounts but they wont work on allowing my account Sherbertlemons0 to buy stuff how do create a new account to be the adult of Sherbertlemons0 as it wont let me buy stuff
please help me anybody as I have spent £75 this month on stuff for xbox and don't really want to create a new account what do I do and how can I create another new adult account for Sherbertlemons0???
much appreciated Sherbertlemons0 x

 

Account Settings!!

If youre using a child account, you’ll need to sign into an adult account to change the settings. If youre on an adult account and its not saving your setting changes on console, try logging into xbox.com and changing your account settings there.

 

Hey there BrandoPigmaster.

If you set your birthdate to the correct date upon creation of your Xbox Live account, it should automatically transition into an adult account as you mentioned. Where are you seeing that your Xbox Live account is still showing as a child account?