Microsoft Excel Solver Issue

When I use Microsoft Excel on my Macbook Pro, everything works fine, however I encounter an issue when using the Solver function. I generally maximize the window because I like swiping between the different windows to see problems, but when I load the Solver extension within Excel, it defaults back to the Macbook's home screen and does not allow me to move it back to Excel. Basically, the Solver automatically goes off the spreadsheet and onto the Mac's home screen and I have to continually minimize Excel out of full desktop to use it, and it gets quite annoying. Please let me know if there is any way to fix this. Thank you!