You can choose your desired margin type (isolated/cross) and leverage level for each symbol that is available on the client's exchange. In some of the exchanges, the leverage level is set the same for all symbols.
Leverage/ Margin configuration:
By choosing "All Symbols" you will be able to configure all pairs at once. Any previously selected leverages for a specific symbol will be overridden with the new value, but you will be able to change the leverage for a specific symbol later if you wish to do so.
Since different coins have different valid leverage values you will only be able to choose a leverage that is valid for all the coins in the exchange.
Read more about leverage: Margin Trading