If you create a new issue with attachments, all attachments referring to that issue, will automatically be uploaded.
However, you can make adjustments to your attachments i.e. you can delete one or more if you do not need them.
For deleting an attachment, you click on the relevant document and the blue hook disappears. This attachment will then not be uploaded in your Jira issue.
If you do not click anything, all attachments will be automatically uploaded.
Deleting an attachment looks like this. You click on the document you wish to delete and the blue hook disappears. This attachment will not be uploaded in your Jira issue.
In your Jira for Outlook settings you can change the automatic upload of your attachments. For example, you you can set that all attachments are not automatically uploaded. Then, you then need to select each required attachment individually.