There are two methods to customise your Slippage Tolerance.
Method 1:
Input the Slippage Tolerance value manually on your trader order form for a specific order. Please note this method will only apply the tolerance amount for that specific order, in that specific account, and nothing else.
Method 2:
Head to Trading Settings and under Slippage Tolerance, input your preferred tolerance limit. This will set your account-wide Slippage Tolerance across all Market Orders and all contracts within the particular account.
Please note that this method will not override option 1, meaning if you input a Slippage Tolerance for a specific order via the trade form, it will overrule your settings.