Please consider turning on send info to Mozilla before posting a question. This helps us help you.

Was this something that worked before ? If was could see but have no information, no Firefox version, or graphic card info.

Support Volunteers can't make changes to Firefox and the developers do not directly monitor this site. To submit suggestions for new or changed features, may I suggest:

Feedback: https://qsurvey.mozilla.com/s3/FirefoxInput/ Facebook: https://www.facebook.com/Firefox Reddit: https://www.reddit.com/r/firefox/ Twitter: https://twitter.com/firefox

There also is a forum run by the Add-ons team where you may see talk about potential future capabilities of extensions to modify the UI (initially limited to colors, I think, but perhaps more down the road): https://discourse.mozilla-community.org/c/add-ons

Please let us know if this solved your issue or if need further assistance.

Firefox doesn't have a setting to paste spread sheet data like from an Excell file. Firefox places some flavors on the clipboard, but that is only plain text (text/unicode) and possibly some other flavors like text/html depending on where you right-click.