Browser hijackers are a type of malware that can modify the settings of your web browser without your permission. There are several ways in which browser hijackers can get into your PC.
They may come together with a piece of freeware that is supported by malware or potentially unwanted programs. Take Media Downloader for example, it contains the installer of the Taplika browser hijacker. If you choose the Quick Installation, by default you will set Taplika as your homepage, default search and as your default new tab on all compatible browsers and allow Taplika browser to install on your PC.
So, when installing software on your PC, you should always select the Custom/Advanced mode and check if there are any additional programs that are being installed along with the main software. If there are, deselect them.
Besides, you need to carefully read the EULA appearing during the setup process. There may be information about installing a potentially unwanted program hidden in that end user license agreement.
Browser hijacker can also enter your PC through spam e-mails, suspicious pop-ups, or malicious websites. So you need to learn the basic knowledge about e-mail security; avoid clicking on pop-ups that appear out of nowhere; try not to visit untrustworthy websites. But the most important is that you should safeguard your computer with a powerful anti-malware program and keep the real-time protection feature activated.