How to change WordPress links format

Permalinks are the permanent URLs to your individual weblog posts, as well as categories and other lists of weblog postings. A permalink is what another weblogger will use to link to your article (or section), or how you might send a link to your story in an e-mail message.

Selecting permalink structure

1. Open WordPress admin panel

2. Go to Settings>Permalinks

(click to enlarge)

You can choose one of the “common” structures or enter your own in the “Custom structure” field using the structure tags

Note: You never, ever put your site url in the permalinks slot. You must use one of the structure tags, or a combination of tags only.

Permalink Tags

%year%

The year of the post, four digits, for example 2004

 %monthnum%

Month of the year, for example 05

 %day%

Day of the month, for example 28

 %hour%

Hour of the day, for example 15

 %minute%

Minute of the hour, for example 43

 %second%

Second of the minute, for example 33

 %post_id%

The unique ID # of the post, for example 423

 %postname%

A sanitized version of the title of the post (post slug field on Edit Post/Page panel).

 %category%

A sanitized version of the category name (category slug field on New/Edit Category panel). Nested sub-categories appear as nested directories in the URI.

 %tag%

A sanitized version of the tag name (tag slug field on New/Edit Tag panel).

 %author%

A sanitized version of the author name.

Note: For performance reasons, it is not a good idea to start your permalink structure with the category, tag, author, or postname fields.

Feel free to check the detailed video tutorial below:
How to use WordPress Media Library