You can not change the cTrader account types, “Netted” to/from “Hedged”.
You can choose the account type when you open the account. (in case a broker doesn’t offer this option, then traders cannot choose by themselves)
In many cases, the broker restricts the account type to either “Netted” or “Hedged”, thus traders cannot choose the account type.
If you wish to change the account type of cTrader, you may need to contact your broker.