| You cannot store digital signals any louder without distortion.|
You can if the input level is set unusually low. This applies to both digital and analogue recording. The amplitude, and therefore the volume, is stored digitally as well as the frequency. If the input is low the resulting information will stored with have low volume that cannot be amplified without severe distortion.
If the input level didn't matter there would be no need input level meters in digital audio recording applications I mention this because the OP is using a recording application that came with the laptop which is probably the Windows Sound Recorder which does not have an input level meter and he might not realise that the input level is set unusually low. which will result in his low output.