Adding names to photos, text size varies widely

I have a large collection of family pictures. Sometimes the name gets separated from the picture so I started using Faststone Image Viewer to add to the canvas (bottom) (50 pixels). Then I can type the person's name. These are great for ancestry write-ups.

I then put a picture border around the page in Microsoft Word 2013, so picture sizes and the names should be the same. About 5 pictures across top and bottom and around 7 on left and right side. Then, text in the middle of the page. Looks really great!

However, the text (name) on some pictures are too large, and others are too small. I get very few Goldilocks (just right). I discovered I cannot use the same text size for all the pictures. But I don't know why or how to fix this.

I know I can put names right under the picture in Word, but then I have to group text/picture if I need to move any. Too tedious to do when there are so many pictures. FastStone really does a good job of clear, smooth text and I would prefer to use that. (Free version)

I don't know if dots per inch would affect the size, no two pictures seem to be alike. These are older pix other family members have scanned, other pictures are more current and taken with digital cameras, or smart phone. I can change the size of the picture easily, but if it has a name inserted on it, then it is either too small to read or so large that it is distracting.

I find that typing the name on the original digital file then dragging to resize in Word makes a more clear picture than if I resized the picture to the final size first then typing in the name. I never know when I would need to put the picture in a different layout and it gives a better picture to drag the original size picture to make smaller rather than drag to increase size of picture.

Any suggestions? I am using Windows 10

a picture would help us understand the issue!

Been to town all day, will work on the picture tomorrow. I tried a print screen of the border-of-pictures, cropped one out and compared it with the same picture in Word. It was slightly larger.