The search tool for searching out posts in this forum leaves a lot to be desired.
You were getting data changes because you were entering the barcode number into your barcode field while in browse mode--don't know if you were scanning a barcode or typing it in, but the result is the same.
You can use a separate search field with global storage specified and a script that uses the data in that field to perform a find. See this thread for examples: Scripted Find Examples
You can set up a relationship and a portal so that entering/scanning the barcode into the separate search field display any matching records in the portal.
Or you can enter find mode, enter or scan your barcode into the barcode field--not a separate search field and then perform a find to to find your record(s). BUT DO NOT DO THIS WHILE IN BROWSE MODE OR YOU WILL ALTER THE BARCODE OF THE CURRENT RECORD INSTEAD OF SEARCHING FOR A RECORD OF THAT BARCODE. The risk of accidentally doing this is one of the reasons for using a separate search field.