I would like to know how to store something when you use check box and later access it when checkbox state changes.
I tried store array as global but when script runs again what i stored is reseted to empty array.
I also tried propeties but it can only store strings. So if anybody know how to store attachments i would be glad.
There are lots of ways on how this can be approached. Either you can store data to a spreadsheet and build scripts based on the Google Sheet Data by referring to this document.
If it's a file were talking about you can use DriveApp using the method createFile() from a given Blob of arbitrary data. Documentation here.
Or, you can connect to an external database using JDBC Service as reference here in this documentation.