>I am using:
>
>LOCATE FOR 'ARNOL' $ UPPER(MYTEXTBOX)
>
>In a indexed table, is there a way to use "seek"
>in the code below instead of locate ?

Seek not - it works from the beginning of the key, i.e. seek() is actually a fast version of "locate for {keyexpression}=lcStringToFind" (and the equal sign behaves with the usual "to the length of the right one" rules).

You may try SQL version of that, by either doing

select ... where 'ARNOL' $ UPPER(MYTEXTBOX)

or

select ... where UPPER(MYTEXTBOX) like '%ARNOL%'

Not sure any of this is optimizable, even if you have a tag on UPPER(MYTEXTBOX).