Method 1:
Resizing with PicResize is what I find the easiest.
Step 1:
https://i.postimg.cc/LXj9QjTp/W1.png
Search "PicResize"
Step 2:
https://i.postimg.cc/43JQx1Y8/W2.png
Click "Drag or Drop files"
Step 3:
https://i.postimg.cc/PxJcPHCF/W3.png
Choose a file, then click "Continue to Edit Picture"
Step 4:
https://i.postimg.cc/0NDGnHL2/W4.png
Then click the, "Select a new size for your picture" box, and select, "Custom Size". Type, 300 in one box, and 300 in the next. Make sure you are using "Pixels". I prefer using "PNG". Then, click "I'm Done! Resize My Picture!"
Step 5:
https://i.postimg.cc/rsQ7mpJb/W5.png
Then, you may look at your picture, by clicking, "View Image". Then, select "Save to Disk". Done! Keep it in a memorable place! Please Remember the name of the saved file. The the file will be named with "rsz" at the beginning.
(If your image was less than 300 pixels height of length, then you won't get to resize it)