Not a lot of info given, but I'll take a stab.
1. Click the enlarge button (middle of the 3 at the top right corner. It's a square.
2. Drag the four edges to the side of the computer. Open another EDGE and do the same. Close the 1st one first then the 2nd one.
3. Create a "shortcut" (from the Apps Section) for EDGE on the Desktop .
Click on Properties. Towards the bottom should be a drop down with open with "normal
window". Click on that. Select maximized. Open EDGE. If it's good OK. The correct setting is normal, so there's a small error somewhere. Try sfc /scannow if not OK.
Bill