You can change the amount of resources allocated to a content's sandbox by selecting Stack in the left side menu and scrolling to the Sandbox Resources section.
The amount of resources allocated to a content's sandbox are strictly limited based on the Tiers below:
5% Priority 1
10% Priority 2
10% Priority 3
Contents using a Tier 2 or Tier 3 sandbox will incur a 2x and 4x billable minute multiple, respectively.