My first thought is the "auto punctuate" feature many digital keyboards have, including Samsung's default. [link|https://us.community.samsung.com/t5/Galaxy-S-Phones/How-can-I-stop-the-space-bar-from-placing-a-period-on-keyboard/td-p/1458847|Here is a link] to the Samsung community forums where someone demonstrates how to disable this feature. If this doesn't solve your problem, please provide additional information so we can help you better!