Go to Rollup Helper and Create a new Rollup Helper Setting
The first choice will be to select the target object, the object you will Rollup to, this will be Account.
Next will be to select the Target field, which will be the Largest Quoted Amount field which was just created.
On the Step 3 page of the Rollup Creation Process
Select Quote as the child Object and use default relationship field: Account ID - Quote.AccountId
Select Rollup Type: Maximum
As long as there are not any quotes you would like to have excluded from the calculation, you do not need to create a filter.
After the filter has been created, or if you do not need one you can use the Save and Run to complete the rollup!