Create an Album of images for your slideshow, then double-click on the Album to view the contents.

Click the ellipsis icon to access the More menu, select Sort by, and choose Manual. This will allow you to rearrange your photos in the Album.

Right-click on an image in your album or tap the kebab icon to access the Actions menu and choose Select > All.

Click the Share icon and choose Export as Video.

Choose the option you'd like to use, click the Export button, choose where to save your slideshow on your hard drive, then click Save.