I got a charge $18:98 that I did not change

If the only indication of the charges is from an email or text, be aware that it may be a phishing attempt to get you to log in to a site that appears to be Apple and divulge your password or credit card information. Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

You can use the following instructions to determine if it is a real charge, what it is for, and to report a problem: Get help with an item purchased from the App Store, iTunes Store, or iBooks Store - Apple Support

If you have recurring charges for the same amount: View, change, or cancel your subscriptions - Apple Support

Also see: If you see 'itunes.com/bill' or an unfamiliar charge on your bank, credit card, or debit statement - Apple Support

You can use the following instructions to determine what the charge is for and to report a problem if needed: Get help with an item purchased from the App Store, iTunes Store, or iBooks Store - Apple Support

Also see: If you see 'itunes.com/bill' or an unfamiliar charge on your bank, credit card, or debit statement - Apple Support