Go to https://account.jagex.com/manage and enter the Email & Password that has been delivered to your purchase email.
Upon logging in, Jagex will request either a code from your Email or your Authenticator App, choose 'Authenticator app'.
When you purchase the account you will be provided with an 'OTP Key', it looks like this: ARBOSWXQJVGATTWDXVAAEXUNJHVYBBSG
You need to copy and paste this into your preferred OTP Code Generator and set the interval to '30 Seconds'. I recommend using: https://totp.danhersam.com/
Click the small Pencil Icon next to the current Email. This will send a Verification Code to the Current Email registered to this account.
To retrieve this code go to https://webmail.eternalaccounts.net/ - Sign in here using your accounts Email & Password and retrieve the Verification Code from your Inbox.
You will be asked to Provide your New Email Address, enter your Email Address and hit 'Continue'. A code will be sent to your Email, retrieve and enter it. Congrats! - Your Email is now in full control.
Once you have secured your Email I highly recommend that you change your password also! To do this you will need to sign-in again with your New Email.
Once done click the small Pencil Icon next to Password. This will send you a Password Reset Link to your accounts registered Email.
Once you receive it enter a strong memorable password and confirm - Congrats your account is now very secure!
* Don't forget to save all this information, I don't keep account information, once it is sold the account is completely out of my hands!
Take account security very seriously? I also recommend that you reset your accounts 'Backup Codes'. These codes are what allow you to get back into your account just in-case you forget your Authentication Methods.
Log back into your account and look for the heading 'Backup Codes', you will see 3 Dots (...), click them and select 'Replace'. You will be asked to Sign-in again and to enter either your OTP Auth Code or a code sent to your Email Address.
Once you've signed in again you will get a Confirmation window. Click 'Confirm'. You will receive 10 brand new Account Recovery Codes. Click the Checkbox and click Confirm - Well done your account is now bulletproof!
PLEASE REMEMBER TO SECURE THESE CODES SOMEWHERE SAFE, THEY ARE ABSOLUTELY CRITICAL FOR GETTING BACK INTO YOUR ACCOUNT IF YOU LOSE ACCESS TO YOUR EMAIL OR LOSE YOUR OTP KEY!