You can format dates into many different ways in Google sheets such as the short date and the long date etc. Please see below for details:
Step 1: Select the dates you want to change the formats;
Step 2: Click the "Format" tab from the ribbon, and click the "Number" command from the drop-down list;
Step 3: In the extended list, click "More formats" at the bottom and then "More date and time formats";
Step 4: In the "Custom date and time formats" window, change the date format.
1. To have the short date format "yyyy-mm-dd", click "1930-08-05" from the list; and if you cannot find, then click any format and change it to the date format "Year(1930)-Month(08)-Day(05)";
2. To have the long date format "mmmm d, yyyy", click "August 5, 1930" from the list; and if you cannot find, then click any format and change it to the date format "Month(August) Day(5), Year(1930)".
Please note that you have multiple options for each part of the date, e.g., there are 5 "Month" options.