More often using a mobile phone than a laptop, because I am more outside the house.
When i am back at home and before go to bed at night I use a laptop
Trading with mobile is risky just like see the case of OP you might enter wrong amount and will lose all the money with silly mistake so I suggest you to bring your big screen equipment with you which is laptop or the tablet where you can see all the trading window without any difficulties.
He might still use phone but its better he limits his activities on phone when it comes to trading with it, you know we have lots of trader that are also on the go with stable internet, imagine I am inside a bus and need to trade, it would be difficult to start operating my laptop in a bus for trade that cannot wait to I get to a location where I can open my laptop, take for example too, a site engineer that need to move round and not stable on a spot but with his phones, he can still keep his eyes on the trade, just need to be careful as you said not to enter a wrong trade.