This video tutorial will teach you the difference between absolute referencing and mixed referencing. When you want to lock down the rows and columns the formula will have a dollar sign in front of the column and row. Example =$A$1.
When you only want to reference a locking of the row number the formula would look like this =A$1.
When you only want to reference a locking of the column the formula would look like this =$A1.
So a mixed reference is part absolute and part relative.
The dollar sign placement is important as it comes before the position (row/column) you want to make absolute or locked.
Practice with my YouTube example by clicking here. Absolute Referencing Mixed Reference YouTube example.