@fufulina has a fair point. For us the whole point of ds having a bank account was to teach him responsibility with guidance. Every parent has the worries of their financially inexperienced dc potentially overspending, whether that is due to showing off, peer pressure, vulnerabilities or a dozen other reasons. There are ways to handle that while allowing them to take on responsibility at the same time. ime kids won't learn to step up when you give them responsibilities if they know you don't trust them and giving him a grown up account while saying I have the password and I am watching you takes the shine off that growing up step for them.
The main ways of protecting them are - 1) don't put anything more than the money they are free to spend / pocket money in their account so it is very low risk 2) talk to them about how it is going/or go through their spending together with them for the first couple of months, 3) let them bear the consequences and learn the lessons of any mistakes (worth losing a few quid for them to learn invaluable lessons).
ds had a Nationwide Flexi one account and savings account and he could transfer between them. There wasn't much in the savings account just somewhere to hold birthday/christmas money and it was there to encourage him to budget and keep it for something special/big he wanted rather the fritter it away (didn't always work, but he learnt from that too when the next FIFA game came out and his friends had it and he couldn't afford it anymore, or his friends were going out somewhere he couldn't afford to).
It is something to reflect on from someone who has been through it before and whose dc made and learnt from some cracking mistakes - lessons that I can see positively influence his attitude to spending his own money now he is at uni (he has no problems spending my money when he has the chance!). I am not telling you how to parent.
When ds was younger I could sign into his Nationwide account on a desktop if I had a note of the password. Nationwide don't need to know you are doing this.