1. Right Click the Pixieset Plugin Manager under the Publish Services Tab and select Edit Settings
2. From there you will be able to see and adjust the file settings and file size. As well as see how much space is left on the subscription of your account (this is handy if you receive a cannot upload error message, it will allow you to check if you have reached the allotted space for your account.)
Once you have set or adjusted your settings, you can simply hit save for it to take affect for all new exports.