Is the landlord required to return the full security deposit to tenants ( or partial security deposit with itemized list of what deductions were made) within 21 days? 

At the end of the lease term, it's a simple as printing that spreadsheet so it shows all itemized deductions from the security deposit.

I wanted to see what other people were using to set up their security deposit accounts? 

It tracks deposits over the past 12 months, showing average balances, current available funds, and both recurring and one-time deposits.

If Person A had any claim to the deposit, it would have been right after they left, which apparently was over a year ago.Your agreement is with Person B and that's who you would return the deposit to.

However, the damage as described is greater than normal wear and tear and so, deducting from the security deposit for repairs is reasonable.

Have a rental in the Phoenix metro. Rented the property with a professionally cleaned carpet. The tenant left with a not so clean house. We deducted the cost of cleaning the home, the carpet, and some other drywall an...

Last year I opened a Roth IRA with Fidelity and contributed the $7,000 max, forgetting I also have a Roth with Acorns which $1,400 was contributed to through weekly direct deposit.

We just offered on a house with all contingencies waived and after the depositing the initial deposit we realize they are counting 300 sqft of completely unfinished room with no ceiling hvac huge  unit in it and with all sorts of pipes taking floor space and ceiling space as a room of 300 sq ft.This is misrepresentation as it makes the house so much smaller in the basement and we are already paying above asking by 50K.

We have a modest security deposit collected up front along with 1st month's rent and the cleaning fee.