Database NOT found, why?

[OptimalDesigns]

"Table 'XXX.settings' doesn't exist" means what?  How to fix this warning?  XXX is my database and it does exist, so where is the problem?

[Shambles]

It's not saying your database doesn't exist - it's saying that table doesn't exist.

Is that the complete error message, or does it actually say XXX.smf_settings?

PS, you posted in the section for issues with the SM.org website.

[Livaco]

One of the tables will be missing from your forum database. try getting the code and add it to your database.

PS Like shambles said its the wrong board

[OptimalDesigns]

Is that the complete error message, or does it actually say XXX.smf_settings?

No "smf_" ... just "XXX.settings" ... where are such tables stored, in /forum or my server with my database?

[Livaco]

where are such tables stored, in /forum or my server with my database?

Your SQL Database

[Kindred]

and, based on the error, it would appear that you set up your forum to use tables without a prefix...   that was likely a poor choice.

However... it appears that you settings table has been removed or made inaccessible for some reason.
Check that the table actually exists in your database...   and then check with your host