Can you change your signature? What to update afterwards
Changing your signature is usually allowed — the work is in updating banks, IDs and accounts that keep a specimen.
In most countries there is no rule that you must keep the signature you had at 16. What matters is that you use your signature consistently and that the places that compare signatures know about the change.
Places that may keep a specimen
Banks (especially for cheques), passport and ID offices, your employer's HR file, and some brokerages or notaries.
How to switch
Practise until the new signature is stable, then update the institutions above. Some will ask you to sign a new specimen card in person.
During the transition
If a document must match an older ID, sign it the old way until the ID is renewed. Check the rules with the institution — this page is general information, not legal advice.