Hardware issues
Most router and modem manufacturers recommend you update your router every 5 or so years. If your router is more than 5 years old, you may wish to consider investing in a new, fresher model. This will likely speed up your upload speed. However, before making upgrades to your router's firmware, you may want to consider placing your router in a different part of the house.
Internet provider is restricting your internet speed
Internet service providers (ISPS) are potentially responsible for restricting your internet upload and download speed. The best way to figure this out is to run a speed test that can determine the speed of your wireless connection. If its too slow for your liking, you may want to opt for a different internet plan capable of higher mbps transfers that would in turn reduce your slow upload speed issues.
Too many connected devices
It's often the case that your bandwidth is being overloaded due to there being too many devices connected at once. If this is the case, disconnecting some devices will likely improve the speed of your internet connection, and result in good upload speeds due to your wifi being less crowded.
Malware
Another reason why your internet upload speed is too slow might be that viruses and other malware installed are on your computer, or potentially even on your router, or modem. If this is the case then checking your DNS settings and installing some form of anti-malware/antivirus software would hopefully solve the problem of slower upload speeds.