Your spreadsheet has a column with dates, starting with say A4 with 1/2/2019 and you want to replace the dates in the this and the rest of the column with the next year, e.g., 2020.

1. Insert new (temporary) column to right of dates column (it's a new and blank column B)
2. Apply this here formula in new column B next to the first date you want to change. Say column A row 4 has 1/2/2019. Put this formula in column B row 4:

   =DATE(year(A4)+1,month(A4),day(A4))

3. Select the cell B4 and drag down to select all rows in column B that you want to use to replace column A's dates
4. Control-D (pastes the formula down the column). You should see the updated dates in this new column B.
5. Select all of the column B cells you have changed, and copy to clipboard
6. Put cursor in first date you want to change, that is, in cell A4
7. Edit > Paste Special > Paste Special. Make sure Paste all is not checked and Formula is not checked. Paste. OK the overwrite.
8. You can now safely delete this column B.

It's easier to name a cell so that (a) references make sense and (b) you can move the cell but retain the reference.
for example referencing payment totals when adding/deleting rows/columns around them.

How to name a cell

• Select the cell
• Upper-left corner, see the letter-number (e.g., D23) of the cell. Type the name you want in this spot (e.g., CCjan)
• Repeat as needed

Alternatively you can select the cell, Sheet > Named Ranges and Expressions > Define

How to use a named cell

• Select the cell to reference the name
• Type = and start to type the cell name (e.g, C C j a)
• When the desired name is the only choice, press enter.

Note that names can be used within formulas.