In my experience you would set up one COA, and multiple bank accounts, each bank account: Acct #8978 -6611 xyz st.. Under the Fixed Assets you would input a description for each property address you manage/own. Security Deposit's would be held separately, with a description of each property (address), as a long term liability if you lease these properties for more than one year. Any expenses that pertain to the properties would be set up in the same COA.
Run a report: based on the bank account number designated to the property, or run a report for the Fixed Asset, and then the "expenses," which would be the small stuff you purchase (usually expense are the items that are less than $1,000.00), you would run an expense report. From the COA list, you can alway right click on the item in your COA's, and then run a yearly, monthly, quarterly report by customizing the report, based on your needs.
You could do it, like I do:
Fixed Asset: 620 N. Dallas Rd., Unit B (property address, then Unit if commercial lease).
Under the Fixed Asset, I have "sub categories," for the expenses such as:
Repairs & Maintenance Exp-620 N. Dallas Rd., Unit B
Alarm Exp.-620 N. Dallas Rd., Unit B
Utilities Exp.-620 N. Dallas Rd., Unit B
Anything "major" such as a new roof of $23,000, or new carpet inside @ $11,350 :
Building Improvements-620 N. Dallas Rd., Unit B
These descriptors for your COAs, are for your CPA, or EA to discuss with you. You do not want too many, but you also don't want to miscategorize your transactions, either.
What version of QBO do you have? If you have the Plus version then you could use classes to track your income and expenses per property. For each transaction you would add the class of the property it pertains to. Then when you run the Profit & Loss by Class report it will clearly show you your numbers for each separate property. You can also create a Balance Sheet by Class to do the same thing.