Hi Klaro. I'm Greg, an installation specialist, 10 years awarded Windows MVP, and Volunteer Moderator, here to help you.
What you want is a brower's Zoom function normally found in Settings, but also available in most windows by holding Ctrl button and rolling the mouse wheel slowly, or tapping the + or - key. Frame the Window so it is large enough to read comfortably while you're setting back in chair, but also fits within the windows frame. Then it should remember the setting.
Also make sure you have the latest Display adapter driver from the PC maker's Support Downloads webpage for your exact model. While there check for the latest Chipset, BIOS, Sound, Network, USB3, Bluetooth and all other drivers to compare with the version/date installled for that device in Device Manager reached by right clicking the Start Menu.
Then in Settings > System > Display set the screen resolution to recommended to make the images sharpest. If this does not make them large enough, you can readjust the screen resolution to another, or set a custom Scaling, starting around 112-117% to see if that's sufficient.
I hope this helps. Feel free to ask back any questions and keep me posted. If you'll wait to rate whether my post resolved your problem, I will keep working with you until it's resolved.
______________________________________________
Standard Disclaimer: There are links to non-Microsoft websites. The pages appear to be providing accurate, safe information. Watch out for ads on the sites that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the sites before you decide to download and install it.