Merge columns to replace existing columns. In Query Editor, ensure that the columns that you want to merge are of Text data type. Right-click a column header, and select Change Type > Text from the context menu. Select two or more columns to be merged. Press the CTRL key, and then click on the column headers to select the columns that you want to merge.
Normally we figure out someone's age with current date subtracting the given birth date. So does it in Excel. Step 1: Enter current date in a blank cell, such as 2016/4/7 in Cell B2. Step 2: In another blank cell (says cell C2), enter the formula =INT((B2-A2)/365), and press the Enter key.
Fortunately you can easily change it. If you go to https://appleid.apple.com and login using their account details, in the Password and Security section, you can change the year of their birth. 1/1/2001 works fine, I think the key is that they need to be over 13 to change from Adult to Child account.