There are 2 rotation options in Soda PDF.
In the View Module you will see a Rotate section containing a Left and Right option. Choosing either will rotate your document 90° to the left or right. This rotation is superficial and does not actually modify the document in any way. This means that even if you save the file, when it is opened the rotation orientation will not change.
To actually rotate a page, choose the Rotate option in the Edit Module.
In the window that opens choose which pages should be rotated. Then choose your orientation. The A in the upright position represents 0 degrees. You can rotate your page by selecting the rotated A that best reflects the angle of rotation. When you are ready you should click on Rotate.
When you save your file, the changes will be retained.