The auto index on a linked table has turned -ve Base 7 Debian10

The auto index on a linked table has turned -ve. Using Base 7.0.3 front end on mariadb 10.3.23 Debian10
Have a form for adding data with several sub forms linked to tables with Auto Increment Index’s which worked for 127 entries then turned -ve and went backwards to 0. Now cannot add data because it will duplicate the Auto index number (+1 )is already in use.

Hello,

The problem is with the data type assigned to the auto increment field. I can duplicate with MySQL using a tinyint(1) field type. This only allows 127 entries. It does not go backwards. You can only go to earlier number by resetting the increment number but that will still give duplicates.

You need to change the Type of the field. Why not just use INT?