Tax Refund in top left is showing small tax refund prior to entering charitable donations. Once charitable donations entered, amount of refund not being updated. ????

Donations are a non-refundable tax credit. In other words, they can be used to reduce your balance owing but can't result in a refund.

You can carry forward unused donations up to 5 years, so save them for a year when you'll need them to reduce your tax payable.

For info: https://www.canada.ca/en/revenue-agency/services/charities-giving/giving-charity-information-donors/...