Hi,
Have a check with this:
1 Upload and install this plugin:
-> https://www.ads-software.com/extend/plugins/filosofo-old-style-upload/
2 Go to Options > Uploads.
3 Enter your destination directory. I think the best is to use your images folder in your theme folder so that any images you upload will be in an easily portable place. So the path could be something like /home/server/public_html/wp-content/themes/themefolder/images. The plugin will suggest a path, and it is usually right.
4 Enter the URI of the folder. It’s something like https://www.yoursite.com/wp-content/themes/themefolder/images.
5 You might as well up your maximum file size. I make it 500 kb.
6 Allowed file extensions: jpg, jpeg, gif, png,
7 Minimum level to upload: I leave it at 6 since I have no idea what this means.
8 Click Update Options.
Now create a post with thumbnails:
1. Create an image for your post with the right width and height. The size of the image depends only on the design of your site and where it is going to appear.
2. Go into the admin of your site. Click on Upload (it’s on the upper nav bar).
3. Select the file you are uploading, select No Thanks so it won’t create a thumbnail, give it a description (that’s good for Google) and click Upload File.
4. Once it’s uploaded it will show you the entire URL of the image. Note particularly the last part of the link where it says the name of your image, especially if there are any capitals in any part of the name. You will have to enter the exact file name in step 8.
5. Go to Create Posts. Enter your post and title as you wish. Make sure to select the category you have selected as the one that will appear with the thumbnails. Now scroll all the way down to the bottom of the screen where it says Custom Fields. Click on the plus button to expand it.
6. Enter the word Image (with a capital I) in the Key field.
7. In value, enter the exact name of the file you uploaded. For example picture.jpg or image.gif. Click Add Custom Field.
8. Save your post.
Thanks,
Shane G.