A single user name/password for Different wp sites on diff subdomian

Can i do this my installing WordPress MU .

if so how ?
what do i need to do to have a single username/password for each subdomain sites.

How do I do this?

Appreciate all the help I can get

Hi

If all the sites use a shared database, with different tablename prefixes for each site, you can share a common user file using this method

Share users between two blogs
Put them both in the same database with different prefixes. Then choose one of them to be the master user table. Then do this in both wp-config.php files:

define(CUSTOM_USER_TABLE,’wp_users’);
define(CUSTOM_USER_META_TABLE,’wp_usermeta’);

Replace the wp_ with the prefix you want.

Can you please elaborate more ..

Do i have to install all the sites on the same database with different prefixes.

How do i choose a master user table..

Please elaborate more..

thanks in advanced !

Do i have to install all the sites on the same database with different prefixes.

yes

How do i choose a master user table..

you decide which of the sites in that shared database is going to be the master user table and specify its table name in the wp-config.php of all the other sites.

What I suggest is set up 3 more sites as test sites, 3 different subdomains, and see if this method is going to work for you by testing between the 3 test sites. Do NOT just convert your existing sites to this method – you want to see it working on test sites before you do that.

If you decide to convert your existing sites to this method after testing, there are some SQL changes you will need to make to the database in each site on which you have changed the table prefixes – see https://beconfused.com/2007/08/28/how-to-solve-you-do-not-have-sufficient-permissions-to-access-this-page-in-wordpress/