It's fantastic to see you here, @AliS2,
I can share some insights on how certain accounts affect your books. As an overview, QuickBooks Online uses account types as components that tells how transactions hit your books.
Generally speaking, these account types are just categories to organise the data on your reports and financial statements. Your Cost of Sales is the direct cost of doing business, like the production of goods company sells. It is a business expense that is deducted from revenues to calculate gross profit and gross margin. Some example for this category are cost of labour, equipments, and manufacturing overhead.
Regarding the second account, you're referring to as "contractor expense", may I know under which category did you see this? I need some clarification to ensure I am guiding you to the right path.
If this is a regular expense, then these are the cost of the regular operations of business, like utilities. In QuickBooks, you categorise your expenses into different expense accounts for better tracking. Example: Your power and phone bills are expenses.
For further overview, I'll be sharing some links to help you with the account types and categories in QBO:
You can also go to this link where one of our team shared a detailed insights of the accounts used in QuickBooks.
Come back here anytime for additional questions or concerns. I'll be right here to help you. Have a good one!
