If you already optimized all your Media Library by going to Media > Bulk ShortPixel and running the Bulk Optimization, and then you decide you’d like to have some different settings, just
saving the changes will not be enough.
For example, if you optimized all your library in Lossy mode, but then you decide you’d like to have it in Glossy mode, you will have to do the following:
- Go to Settings > ShortPixel and make the changes you wish.
- From Settings > ShortPixel > Tools, restore all the image by clicking on the button “Bulk Restore“.
If you are using ShortPixel Image Optimizer v4.22.10 or lower, the button is located on “Media > Bulk ShortPixel”. 
- Once the bulk restore process is completed, you can run the bulk optimization again from Media > Bulk ShortPixel.
Please notice that this process will consume more credits, and it should be done for every change you make in your settings. Therefore, it is recommended to make sure you have all the desired settings before doing any optimization.