Your account is approved for margin. Maintenance requirement questions?

I am new to investing and opened a brokerage account through TD Ameritrade.

I’ve been purchasing stock with cash deposited into the account.

I noticed today the Maintenance requirement row in the balance sheet, and it made me wonder are they going to charge me for holding stocks?

It says I am approved for margin, and 6 out of the 7 positions I hold are considered marginable.

I’ve read the documentation on the site but man am I over my head on this stuff. I’m considering turning off margin approval on the account.

I purchased all stocks in full with cash, so I do not understand what the maintenance requirement fees would be?
And the maintenance requirement seems to be raising as the stocks go up in value?

Will I be charged if the stocks go down in value? What are the risks?

If I always purchase stocks in full with cash will I ever be charged a fee?

My goal was to have a 0 commission account where I could purchase stocks and only lose money if the stocks depreciated in value. I do not want to deal with other fees and maintenance fees.