The word count shown in the project targets window is based on the compiled output (subject to any settings you have altered via the “Options” button), so reflects what your word count will be with your current compile settings. The project targets window is therefore telling you that you have written 68,537 words against an overall project target of 75,000 words. The target in this case is the number that you have set up for your draft as a whole, via the project targets window, and is unrelated to any targets you have set for individual documents.
The word count shown in the footer of your Scrivenings setting shows, firstly, the actual word count of the documents in that Scrivenings session, then (after the / character) the total of the number of individual document targets for that selection. The 68,537 part is the same as shown in the project target window, which shows that you are looking at the same documents (if there were a discrepancy, it might imply that you had accidentally unchecked “Include in Compile” for a document, for example). The 70,633 part indicates the number of words that you would get if you went into each document in the Scrivenings session one at a time and added up the individual document targets for all these documents. This indicates that although you intend writing 75,000 words in the draft as a whole, you have actually only allocated 70,633 words as individual document targets. You may need to add more documents, or to increase the target word count on existing documents, to bring the draft total up to your intended 75,000.
A simpler example… Suppose my aim is to write a short piece of 1,000 words. I set 1,000 words as my project target, so the project target window will show progress against this. I then create individual documents for Introduction, Middle and Conclusion. I know that I want to allow 150 words for the Introduction and another 150 for the Conclusion, so I set individual document targets of 150 for each of those two documents, using the little target icon in the footer bar. I haven’t really decided how many Middle documents I will create, or how long they will be, so I don’t allocate a target for that at this stage. I start writing, write 200 words, then check my statistics. The project targets window will show 200 words against a target of 1,000. But if I open Introduction, Middle and Conclusion in a Scrivenings session, the footer bar will show 200/300 because I have written 200 words, and the documents included in the session have a total target of 300 words between them.
I hope this clarifies things a bit.
All the best,