Data Amount Settings specifies the amount of historical data that should be downloaded from data feed server (at the first symbol data download). All downloaded data will be stored on local PC (this will be used next time the user will open the application).
Note 1. There is an addition option for DAYly-based data to download all available bars from server.
Note 2. Downloaded data can also be limited by data feed server. For example 'some data feed' server supports only 15 days of minute-based historical data. Then the downloaded data will be limited to 15 days, even if the user will set 60 days in Data Feed settings.