The default number of Featured Image which can be set for each Post & Portfolio item created, is 5.
This value can be increased or decreased by going to Theme Options -> General Settings -> Featured Images
Drag the slider to right to increase the number of Featured Images – the currently maximum number of Featured Images that can be set is 30.
After updating the number of Featured Images, try going to a Post or Portfolio and edit it. You should see the new value being used for the Featured Images.
Written by RockyThemes