Update/Add arrays mongodb collection

By importing JSON to mongodb, I have a record that looks like following:

"_id" : 1,
"salesRecord" : [
    {
        "quarter" : "First",
        "monthly" : [
            {
                "brand" : "Apple",
                "month" : "January",
                "sales" : 8000
            },
            {
                "brand" : "Samsung",
                "month" : "January",
                "sales" : 8500
            }
        ]
    },
    {
        "quarter" : "Second",
        "monthly" : [
            {
                "brand" : "Apple",
                "month" : "April",
                "sales" : 7500
            },
            {
                "brand" : "Samsung",
                "month" : "April",
                "sales" : 7200
            }
        ]
    }
]

Question 1 - Want to update "salesRecord.monthly.sales" = 8000 with "salesRecord.monthly.sales" = 8300 for "salesRecord.monthly.brand" = "Apple" in "salesRecord.monthly.quarter" = "First".

Question 2 - Want to add new "salesRecord.monthly.month" = "May" for "salesRecord.monthly.brand" = "Apple" in "salesRecord.monthly.quarter" = "Second".

Looking for javascript snippet or preferably mongo shell commands. Answers are appreciated, thanks !