Up to 20% of residential votes and up to 70% of absentee votes in Switzerland are cast online. The Swiss system aims to provide individual verifiability by different verification codes. The voters have to carry out verification on their own, making the usability and UX of the interface of great importance. To improve the usability, we first performed an evaluation with 12 human-computer interaction experts to uncover usability weaknesses of the Swiss Internet voting interface. Based on the experts' findings, related work, and an exploratory user study with 36 participants, we propose a redesign that we evaluated in a user study with 49 participants. Our study confirmed that the redesign indeed improves the detection of incorrect votes by 33% and increases the trust and understanding of the voters. Our studies furthermore contribute important lessons for designing verifiable e-voting systems in general.