Tomtrance said

When installing a programm or watching a video: - the icons are always very tiny with the firefox - for internet explorer I don`t have this problem - I have the "flash player" plugin installed, must be linked with this

Your System Details shows;

Installed Plug-ins

Shockwave Flash 16.0 r0

YouTube™ Flash® Player 1.2 (jid1-HAV2inXAnQPIeA@jetpack)

Update your Flash Player v16.0.0.296
https://www.adobe.com/products/flashplayer/distribution3.html

And what do you mean about installing a program.

Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

• Use a compressed image type like PNG or JPG to save the screenshot
• Make sure that you do not exceed the maximum size of 1 MB

The Segoe font has been mentioned as a possible cause of issues with the arrow glyph that YouTube uses. This can be a problem with the used font that doesn't have a glyph for this arrow ("▶:▶") and using another font for this glyph is causing this issue. You won't be able to fix this in Firefox via a new profile or a reinstall.

• /questions/975184 bookmarks drop-down triangles size changed
• /questions/968277 Youtube Tab Play Icon Corrupt

Thank you very much for the answers so far. Updating of the flash player doesn`t work. I did this already.

I am not an expert, but somehow I think: - the problem is not related to my "normal" flash player - it is not "youtube" related. It is for all flash applications - it is related to the flash player plugin for the firefox - With the Internet Explorer the icons have a normal size

Attached you two screenshots screenshot (youtube / video on a newspaper website)