When you create a formula that refers to another cell or range, that cell reference can be relative or absolute. A relative cell reference adjusts to its new location when the formula is copied or moved. An absolute cell reference does not change when the formula is moved.

Select the cell that contains the cell reference that you want to change.

In the formula bar, click the cell reference that you want to change.

Press + T to move through the combinations.
In the following table, the Changes to column reflects how a reference type updates if a formula that contains the reference is copied two cells down and two cells to the right.
Current reference (description): 
Changes to: 
$A$1 (absolute cell reference column and absolute row) 
$A$1 
A$1 (relative cell reference column and absolute row) 
C$1 
$A1 (absolute column and relative row) 
$A3 
A1 (relative column and relative row) 
C3 