Browser software like Google and Firefox are update and upgrade 24/7. The new version has minimal requirement OS 10.9. So you can't install the newer version. Youtube ask for a recent versions. Safari is the worst because it is not upgraded after a new OS is launched, Safari aged faster than FireFox and Google.
What to do: Upgrade to 10.11. This version is the more advanced that your computer can be installed on. This version is compatible with the last version of Google and Firefox, but you need 4G of ram. It is cheap and easy to install.
How to ? You need a external drive, so back up every think. You can't use Time Machine which don't existed on your OS. You can download the 10.11 in from Apple directly on the website. https://support.apple.com/et-ee/HT206886
If you have some money and you don't want to buy a new computer think about a brand new hard drive or a brand new SSD.